Experience-Based Opinion Testimony: Strengthening the Lay Opinion Rule

Pepperdine Law Review Pepperdine Law Review

Volume 39 Issue 3 Article 1

4-15-2012

Experience-Based Opinion Testimony: Strengthening the Lay Experience-Based Opinion Testimony: Strengthening the Lay

Opinion Rule Opinion Rule

Anne Bowen Poulin

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Experience-Based Opinion

Testimony: Strengthening the

Lay Opinion Rule

Anne Bowen Poulin*

INTRODUCTION

II. OPINION TESTIMONY UNDER THE RULES OF EVIDENCE

A. Lay Opinion—Rule 701

1. Based on the Perception of the Witness

2. Rationally Based on the Witness’s Perception

3. Helpful

4. Not Based on Scientific, Technical, or Other

Specialized Knowledge

B. Expert Testimony—Rule 702

C. Delineating the Difference

III. THE LINE BETWEEN LAY AND EXPERT OPINION: WHY DOES IT

MATTER?

A. Evaluation of the Opinion

B. Basis of the Opinion

C. Disclosure of the Basis to the Court and Jury

1. Disclosure to the Court

2. Disclosure to the Jury

D. Form of Testimony: The Hypothetical Question

E. Pretrial Disclosure Requirements

F. Deference Accorded Expert Opinion

IV. THE ROLE OF EXPERIENCE IN ESTABLISHING THE BASIS FOR

OPINION TESTIMONY

A. How Experience Informs Lay Opinion: Similar Happenings

and Other Act Evidence

1. Similar Happenings and Lay Opinion

* Professor of Law, Villanova University School of Law. I am indebted to Keri Engelman,

Jacqueline Gorbey, Kristin Mancuso, and Angela Hennesy for their excellent research assistance, to

my colleague Professor Louis Sirico for his helpful comments, and to Villanova University School

of Law for its generous support.

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2. Other Act Evidence and Lay Opinion

3. Evidence of Third Party Conduct and Lay Opinion

B. How Experience Informs Expert Opinion

V. THE RISK OF ADMITTING OPINION BASED ON EXPERIENCE ALONE

VI. SCRUTINIZING EXPERIENCE-BASED OPINION: APPLYING RULE 701

WITH

BITE

A. Evaluate Experience-Based Opinion as Lay Opinion

B. Be Skeptical of Claimed Expertise Based on Shared

Experience

C. Evaluate the Fit Between the Witness’s Experience and the

Opinion

D. Limit Opinion Based on Third Party Conduct

E. Prohibit Over-Claiming

VII. CONCLUSION

I. INTRODUCTION

Consider the familiar expert witness scene from the movie My Cousin

Vinny. Vinny, played by Joe Pesci, calls as a witness Mona Lisa Vito,

played by Marisa Tomei. Her experience as an auto mechanic is held to

qualify her as an expert in general automotive knowledge. The court allows

her to testify that the set of tire tracks made by the fleeing felons’ car could

not have been made by the defendant’s car because only a car with

positraction could have left those tracks. Her testimony leads to the

dismissal of all charges. But is she an expert? Should she be given the

latitude accorded an expert to base her testimony on information not

personally known to her and to express an opinion without clarifying its

basis for the jury? Or is she a lay witness with an unusual experience base

and therefore limited to conclusions rationally derived from her base of

knowledge?

Take an example of typical testimony offered as expert opinion in a

prosecution for a narcotics violation. The defendant is charged with illegal

distribution of cocaine, but claims he is not a drug dealer. At trial, the

prosecution calls a law enforcement agent to testify that certain aspects of

the defendant’s conduct were consistent with the behavior of an experienced

drug dealer. Specifically, the agent opines that when the defendant circled

the parking lot before meeting with the undercover agents, he was engaging

in counter-surveillance, that the defendant’s use of a rental car is the mark of

an experienced drug dealer, and that, when the defendant spoke with the

informant to set up the sale, he used the coded language of a drug dealer.

The law enforcement witness bases these opinions on experience

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investigating drug cases. Is the opinion testimony admissible? Should the

court evaluate the evidence as expert or as lay opinion?

Consider experience-based testimony offered on the question of design

defect. The plaintiff lost his leg when he was hit by a car while riding a

motorcycle. He claims that the motorcycle was defectively designed

because it did not have crash bars. Experts dispute the efficacy of the crash

bars used on police motorcycles. To support his claim, the plaintiff calls a

former police chief who has served on motorcycle patrol and has

investigated motorcycle accidents. The witness’s opinion is that police

motorcycle crash bars are effective. The witness has no scientific or

engineering expertise in motorcycle design and limited experience with the

type of motorcycle the plaintiff was riding at the time of the accident.

Should the court evaluate the offered testimony as expert opinion or as lay

opinion? Is it admissible?

Finding the line between expert and lay opinion testimony is not always

easy.

Determining where experience-based opinion falls on this spectrum

has proven particularly challenging to the courts. Opinion based on the

witness’s unusual experience base does not always fit neatly into either

category. In some cases, the court undervalues relevant experience as a

basis for opinion, either lay or expert. In others, the court defers too readily

to the claim that a witness’s experience qualifies the witness to provide an

opinion, often treating experience as sufficient to establish expertise.

1. This hypothetical is based on United States v. Figueroa-Lopez, 125 F.3d 1241 (9th

Cir.

1997) (discussed infra note 179 and accompanying text). In Figueroa-Lopez, the Ninth Circuit

concluded that the testimony should have been evaluated as expert opinion and excluded because the

prosecution did not provide the required pretrial notice. Id. at 1246.

2. This hypothetical is based on Satcher v. Honda Motor Co., 52 F.3d 1311, 1316–18 (5th

Cir.

1995) (discussed infra at notes 183–190 and accompanying text). The facts of that case are detailed

in the district court opinion, Satcher v. Honda Motor Co., 758 F. Supp. 393 (S.D. Miss. 1991), rev’d,

984 F.2d 135 (5th Cir. 1993). In Satcher, the Fifth Circuit held that the testimony was admissible

expert opinion. Satcher, 52 F.3d at 1317–18.

3. See United States v. Colón Osorio, 360 F.3d 48, 52–53 (1st Cir. 2004); Downeast Ventures,

Ltd. v. Wash. Cnty., 450 F. Supp. 2d 106, 110–11 (D. Me. 2006); Falconer v. Penn Mar., Inc., 421 F.

Supp. 2d 190, 208 (D. Me. 2006) (noting that the line between lay and expert testimony is not

always easy to draw); State v. Ellis, 547 S.E.2d 490, 493 (S.C. 2001) (dissent disagreeing with

majority conclusion that officer’s testimony went beyond his expertise and arguing it was

permissible lay opinion); 1 K

ENNETH S. BROUN ET AL., MCCORMICK ON EVIDENCE § 11, at 59 (6th

ed. 2006) (recognizing difficulty); Brandon L. Bigelow, Summary and Expert Witnesses: A

Distinction with a Difference, 9 S

UFFOLK J. TRIAL & APP. ADVOC. 1, 1 (2004) (discussing confusion

that can arise at trial);

Daniel J. Capra, Distinguishing Between Lay Witnesses and Experts, N.Y.

L.J., Mar. 13, 1998, at 3 [hereinafter Capra, Distinguishing Between Lay Witnesses] (discussing

difficulty of delineating the line under pre-amendment rules); David Martinez & Bree Arlyn-Pessin,

Undesignated Hitters, L.A.

LAW., Feb. 26, 2004, at 28 (referring to the “often blurry distinction”).

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The Federal Rules of Evidence (the Rules) were amended in 2000,

adopting specific, more stringent requirements for expert testimony and

hardening the line between lay and expert opinion. Expert opinion

testimony is now admissible only if based on reliable methodology, whereas

lay opinion must merely be rationally derived using everyday reasoning.

The decisions applying these rules do not strike the right balance with regard

to experience-based opinion. Too often, courts allow opinion testimony

simply because the witness has an unusual base of experience, either

accepting a claim of experience-based expertise at face value or admitting

experience-based opinion as lay opinion without rigorously applying the

governing rule. As a result, the courts admit unreliable and unwarranted

opinion testimony and grant unqualified witnesses latitude in presenting

opinion accorded only to experts. This Article explains why more

experience-based opinion should be evaluated as lay opinion, and also

argues for increased scrutiny of such lay opinion.

The improper admission of experience-based opinion is particularly

problematic in criminal cases. Law enforcement officers are routinely

permitted to testify as experts based on their law enforcement experience.

4. FED. R. EVID. 701–02.

5. See Miller v. California, 413 U.S. 15 (1973) (permitting law enforcement officer with

specialization in obscenity cases to provide expert testimony regarding the state’s community

standards and whether defendant was in violation of them); United States v. Vann, 336 F. App’x 944

(11th Cir. 2009) (permitting police detective to testify as expert witness regarding drug use and

practice); United States v. Paiva, 892 F.2d 148 (1st Cir. 1989) (using a police officer to provide

expert testimony as to whether substance in question was cocaine); United States v. Brown, 872 F.2d

385, 392 (11th Cir. 1989) (allowing FBI special agent to provide expert testimony regarding “drug

code” interpretation and jargon); Williams v. Evans, No. CV F 08-01586 LJO BAK HC, 2009 WL

1460832, at *31–32 (E.D. Cal. May 26, 2009) (referencing long history of allowing law enforcement

officers to testify as experts on gangs and gang activity); 1 B

ROUN ET AL., supra note 3, § 13, at 70

n.16 (stating that expert witness knowledge may be derived from experience, and listing law

enforcement testimony regarding the modus operandi for various crimes as exemplary of such

experience-based knowledge); 3 M

ICHAEL H. GRAHAM, HANDBOOK OF FEDERAL EVIDENCE § 702:2,

at 74 n.4 (6th ed. 2006) (stating that courts commonly recognize expert testimony of law

enforcement officers). A number of commentators have criticized the use of law enforcement

officers as prosecution experts in criminal cases. See, e.g., Phylis Skloot Bamberger, The Dangerous

Expert Witness, 52 B

ROOK. L. REV. 855 (1986); Joelle Anne Moreno, What Happens When Dirty

Harry Becomes an (Expert) Witness for the Prosecution?, 79 T

UL. L. REV. 1 (2004) (criticizing

courts for allowing prosecution experts to testify without scrutinizing their basis);

D. Michael

Risinger, Navigating Expert Reliability: Are Criminal Standards of Certainty Being Left on the

Dock?, 64 A

LB. L. REV. 99 (2000) (discussing disparity between standards applied to prosecution

experts and those applied to defense experts). The courts’ ready acceptance of questionable law

enforcement expert testimony may be precipitated in part by the courts’ frequent exposure to law

enforcement testimony in hearings on defense motions to suppress evidence on Fourth Amendment

grounds. In such a hearing, evidence is relevant that should not ordinarily be admitted at trial. For

example, evidence concerning the law enforcement officer’s state of mind and understanding based

on prior cases, as well as the defendant’s reputation for drug trafficking can be introduced to support

the prosecution’s claim that the officer had probable cause or reasonable suspicion. Similarly, an

officer can rely on information obtained from other officers when determining whether there is

probable cause. See United States v. Garcia, 413 F.3d 201, 213 (2d Cir. 2005) (discussing the

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The prosecution employs these opinion witnesses to ascribe criminal

significance to otherwise innocent conduct. The prosecution also uses them

to advance and endorse inferences supporting guilt that the prosecution will

argue to the jury at the end of the trial. Most of this law enforcement

testimony should not be admitted as either expert or lay opinion. The courts

should curtail this practice by enforcing the rules governing opinion

testimony, with less deference given to the prosecution’s claims.

Courts should assess all experience-based opinion with greater care.

When a party offers as an expert a witness who has an unusual experience

base, the court should scrutinize the way in which the expert arrived at the

offered inferences. If a witness has a broad base of relevant experience, but

brings no methodology to bear in drawing inferences, the witness’s opinion

should be treated as lay opinion. A witness who is merely applying

everyday reasoning to draw inferences from the combination of the

witness’s experience and the relevant observed facts should not be granted

the latitude accorded an expert. Taking this approach, courts would not

allow a witness to give expert opinion based solely on experience without

determining that the witness had a reliable and specialized mode of analysis,

and had applied it to a reliable basis. Most experience-based opinion would

be evaluated as lay opinion and restricted accordingly.

In addition, the rule governing lay opinion, Rule 701, should be given

more bite. The courts should scrutinize lay opinion to make sure that the

witness’s knowledge supports the inferences reflected in the opinion. Lay

opinion must be rationally related to the witness’s perception. Under the

difference between information pertinent for probable cause and foundation necessary for admissible

lay opinion). Such testimony may also be admissible to explain the reasonableness of an officer’s

actions in civil cases where a law enforcement officer is sued for damages by someone who was the

object of police action. See, e.g., Lawson v. Trowbridge, 153 F.3d 368 (7th

Cir. 1998) (action under

42 U.S.C. § 1983 where key question was whether officer had probable cause). None of these

avenues should be open to the prosecution at trial. While strongly probative on Fourth Amendment

questions, the evidence is both irrelevant and unfairly prejudicial at trial.

6. The problem with the prosecution’s use of experts relates closely to the flaws in the forensic

sciences discussed in the National Academy of Sciences Report. N

AT’L RESEARCH COUNCIL OF THE

NAT’L ACADS., STRENGTHENING FORENSIC SCIENCE IN THE UNITED STATES: A PATH FORWARD

(2009) [hereinafter S

TRENGTHENING FORENSIC SCIENCE]. Law enforcement experts claim

experience and pooled information from within the law enforcement community as a basis for

expertise. But the prosecution does not demonstrate the reliability of the expert opinion for the

particular case and the particular questions addressed by the claimed expert. See also Paul C.

Giannelli, The Admissibility of Laboratory Reports in Criminal Trials: The Reliability of Scientific

Proof, 49 O

HIO ST. L.J. 671 (1988) (discussing unreliability and role of subjective judgment in

forensic analysis); Moreno, supra note 5, at 34–35 (discussing law enforcement testimony regarding

drug jargon interpretation and noting that “there has [never] been a real effort to study or test the

reliability of any drug jargon definitions”).

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rule, the trial court should demand that the opinion reflect inferences that can

fairly be drawn from the facts observed by the witness using everyday

reasoning. Currently, courts permit witnesses to express opinions simply

because they possess unusual experience, without any assurance that their

opinions satisfy these requirements. As a result, they allow the jury to hear

unreliable opinion testimony.

This Article explains why more of the testimony given by experienced

witnesses who inhabit the border between lay and expert status should be

evaluated under the rules governing lay opinion and suggests specific

guidelines for scrutinizing opinion testimony. Section II outlines the law

governing lay and expert opinion and the differentiation between the two

types of opinion. Section III explains why it makes a difference whether an

opinion is evaluated as lay rather than expert. Section IV examines the

relationship between experience and opinion testimony, looking at the ways

in which the witness’s experience may inform the opinion. Section V

highlights the risks entailed in admitting opinion testimony based solely on

experience. Finally, Section VI suggests five guidelines for a court

determining the admissibility of experience-based opinion: (1) the court

should generally determine the admissibility of the opinion under the rules

governing lay opinion; (2) the court should be skeptical of claims that the

witness possesses expertise based on experience and “training,”

understanding that the combination of experience and training does not

necessarily signal that the witness brings reliable methodology to bear on the

facts; (3) the court should scrutinize the fit between the witness’s experience

and the proffered opinion; (4) the court should strictly limit opinion

testimony that draws inferences based on third party conduct; and (5) the

court should preclude witnesses from over-generalizing based on their

experience.

II. O

PINION TESTIMONY UNDER THE RULES OF EVIDENCE

The Federal Rules of Evidence devote an entire article to opinion

testimony. For purposes of this discussion, two rules are critical. Rule 701

defines the requirements for lay opinion testimony.

Rule 702 sets the

parameters for admitting expert testimony.

Both rules were amended in

2000 to demark the line between them more clearly and to assure the

reliability of opinion evidence.

7. See infra Section II.A.

8. See infra Section II.B.

9. See generally S

TRENGTHENING FORENSIC SCIENCE, supra note 6, at 92–95 (discussing 2000

amendment).

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The common law rules that predated the Federal Rules of Evidence

restricted the use of both lay and expert opinion.

When the Federal Rules

of Evidence were enacted in 1975, they relaxed the restrictions on opinion

testimony.

For example, whereas the common law typically restricted the

use of opinion testimony to instances in which the jury could not otherwise

understand the evidence, the Federal Rules of Evidence adopted a lower

threshold for admitting opinion.

Under the rules, opinion evidence can be

10. See 1 EDWARD J. IMWINKELRIED ET AL., COURTROOM CRIMINAL EVIDENCE § 1401, at 591–

605 (4th

ed. 2005) (stating the common law opinion rule and discussing its criticisms); 7 JOHN

HENRY WIGMORE, EVIDENCE IN TRIALS AT COMMON LAW §§ 1919–22, at 14–29 (1978) (criticizing

the opinion rule and advocating for its abandonment).

11. See F

ED. R. EVID. 701 advisory committee’s note (commenting that lay opinion should not

be subjected to the requirement that it be necessary and that “the practical impossibility of

determining by rule what is a ‘fact’” has created problems in the law of evidence); F

ED. R. EVID. 702

advisory committee’s note (noting that the key to admissibility is simply whether the testimony will

assist the trier of fact); see also Bamberger, supra note 5 (discussing liberalization of rules governing

expert testimony). Wigmore criticized the common law rules limiting the admissibility of opinion

evidence and argued that opinion should be admitted more readily. 7 W

IGMORE, supra note 10, §§

1919–22, at 14–29; see also Asplundh Mfg. Div. v. Benton Harbor Eng’g, 57 F.3d 1190, 1195 (3d

Cir. 1995) (discussing Wigmore and other critics); 1 B

ROUN ET AL., supra note 3, § 11, at 55

(discussing Wigmore’s position and suggesting that a number of judges already take the Wigmore

approach). In 1901, Learned Hand explained the rationale for and development of the rules limiting

opinion evidence:

The rule that a witness shall not testify to mere opinion or conclusion is such a rule, and

its origin no doubt was, if we could trace it, due to a gradual recognition by successive

judges of the advantage of curtailing the trial and simplifying the issue by leaving out

redundant matter. I call this redundant because in fact the opinion of the witness upon

the issue can have no useful bearing on the case, and trenches on the jury’s function. It is

the jury that should form the opinion, make the conclusion and say truly—vere dicere—

the fact, not the witness; he merely says what he knows. Therefore this rule of

evidence—if in view of this it may be properly called such—is somewhat different from

those which shut off certain facts actually probative of the issue. Moreover, it was

recognized comparatively early in the history of rules of evidence. For we find Vaughan,

C.J., that great defender of the right of juries to go “on their own knowledge,” well saying

in Bushell’s case in 1671: “The Verdict of a Jury and Evidence of a Witness are very

different things, in the truth and falsehood of them; a Witness swears but to what he hath

heard or seen, generally or more largely, to what hath fallen under his senses. But a

Juryman swears to what he can inferr and conclude from the Testimony of such

Witnesses by the act and force of the Understanding, to be the Fact inquired after, which

differs nothing in the Reason, though much in the punishment, from what a Judge, out of

various Cases consider’d by him, inferrs to be the Law in the Question before him.” The

distinction cannot be put more plainly.

Learned Hand, Historical and Practical Considerations Regarding Expert Testimony, 15 H

ARV. L.

REV. 40, 44–45 (1901) (footnote omitted); see also Edward J. Imwinkelried, The Next Step After

Daubert: Developing a Similarly Epistemological Approach to Ensuring the Reliability of

Nonscientific Expert Testimony, 15 C

ARDOZO L. REV. 2271, 2274–76 (1994) [hereinafter

Imwinkelried, The Next Step] (discussing common law limitations on opinion testimony).

12. The Advisory Committee Notes to Rule 701 comment that “necessity as a standard for

permitting opinions and conclusions has proved too elusive and too unadaptable to particular

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admitted even when the jury could resolve the issues without the assistance

of opinion.

The common law also imposed additional restrictions if expert

testimony represented new technology or science.

Key Supreme Court

decisions in the 1990s changed that approach to expert testimony, requiring

the trial court to assess the reliability of the expert’s approach before

admitting expert testimony.

In Daubert v. Merrell Dow Pharmaceuticals,

Inc.

and Kumho Tire Co. v. Carmichael,

the Court reformulated the test

situations for purposes of satisfactory judicial administration.” 1 BROUN ET AL., supra note 3, § 11,

at 53–54 (discussing evolution away from necessity requirement); 1 I

MWINKELRIED ET AL., supra

note 10, § 1401, at 591–94 (discussing evolution of the law); see also Asplundh, 57 F.3d at 1195–98

(discussing move from common law to rules); David L. Faigman et al., Check Your Crystal Ball at

the Courthouse Door, Please: Exploring the Past, Understanding the Present, and Worrying About

the Future of Scientific Evidence, 15 C

ARDOZO L. REV. 1799 (1994) (discussing evolution of rules

from common law to Daubert); D. Garrison Hill, Lay Witness Opinions, S.C.

LAW., Sept. 2007, at

36 (discussing South Carolina pre-rule law, which permitted opinion only if it was the sole way the

facts could be proven). But see Imwinkelried, The Next Step, supra note 11, at 2271 (suggesting that

lay opinion is admissible only if the witness cannot otherwise convey the information).

13. Rule 701 allows lay opinion if it will help the jury, and Rule 702 allows expert opinion if it

will assist the jury. See 1 B

ROUN ET AL., supra note 3, § 11, at 55 (stating that Rule 701 “codifies

‘convenience’ as the standard” for lay opinion, rather than requiring strict necessity); 1

MWINKELRIED ET AL., supra note 10, § 1401, at 595–96 (noting that, in adopting the “helpfulness”

standard for lay opinion testimony, the federal drafters “explicitly rejected ‘necessity’ as the

standard”); Matthew J. Rita, Rule 701: Admissibility of Opinion Testimony by Lay Witnesses, 26

OLO. LAW., Mar. 1997, at 63 (suggesting that lay opinion is admissible even if the jury could

resolve the case without it).

14. Novel scientific evidence was subjected to the general acceptance test, established in Frye v.

United States, 293 F. 1013, 1014 (D.C. Cir. 1923):

Just when a scientific principle or discovery crosses the line between the experimental

and demonstrable stages is difficult to define. Somewhere in this twilight zone the

evidential force of the principle must be recognized, and while the courts will go a long

way in admitting expert testimony deduced from a well-recognized scientific principle or

discovery, the thing from which the deduction is made must be sufficiently established to

have gained general acceptance in the particular field in which it belongs.

Id.; see also 1 I

MWINKELRIED ET AL., supra note 10, § 606, at 200. Under the general acceptance

test, the trial court did not have to assess the expert’s approach for reliability, but instead turned to

the relevant discipline to determine the acceptance of the methodology.

15. See generally Edward J. Imwinkelried, Evaluating the Reliability of Nonscientific Expert

Testimony: A Partial Answer to the Questions Left Unresolved by Kumho Tire Co. v. Carmichael, 52

E. L. REV. 19, 20–23 (2000) [hereinafter Imwinkelried, Evaluating the Reliability] (discussing

evolution of the law).

16. 509 U.S. 579 (1993). See generally 1 I

MWINKELRIED ET AL., supra note 10, §§ 613–16, at

219–34 (discussing the relevance and application of Daubert); T

HOMAS A. MAUET & WARREN D.

WOLFSON, TRIAL EVIDENCE § 2.3, at 16–17 (4th ed. 2009) (discussing the new emphasis given the

“gatekeeper” function of federal judges following Daubert); David E. Bernstein, Expert Witnesses,

Adversarial Bias, and the (Partial) Failure of the Daubert Revolution, 93 I

OWA L. REV. 451, 467–72

(2008) [hereinafter Bernstein, Expert Witnesses] (describing the development of courts’ gatekeeping

role); Daniel J. Capra, The Daubert Puzzle, 32 G

A. L. REV. 699, 720–23 (1998) (discussing

gatekeeping role established by Daubert); Faigman et al., supra note 12, at 1811–22 (discussing

Daubert).

17. 526 U.S. 137 (1999). See Michael H. Graham, The Expert Witness Predicament:

Determining “Reliable” Under the Gatekeeping Test of Daubert, Kumho, and Proposed Amended

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for admitting expert testimony. It concluded that the Federal Rules did not

codify the general acceptance test.

Instead, the Court read Rule 702 as

requiring that expert testimony be reliable and imposing the role of

gatekeeper on the courts.

In the wake of these decisions, there were heated

debates about how the courts should assess reliability and what types of

evidence were subject to the reliability assessment.

The amendments to the rules on lay and expert opinion in 2000

responded to these decisions and the ensuing debate. The amendments

codified the reliability assessment for expert testimony, mandated that all

expert testimony be subjected to reliability assessment, and also established

a clearer line between expert and lay opinion testimony. The rules protect

against unreliable opinion testimony, whether lay or expert, and give the

court a significant role in assuring the quality of the evidence admitted in

each of the categories.

The court should check the reliability of the way in

which the witness derived the opinion,

and should also make sure that the

Rule 702 of the Federal Rules of Evidence, 54 U. MIAMI L. REV. 317, 332–36 (2000) (discussing

Kumho); Imwinkelried, Evaluating the Reliability, supra note 15, at 24–30 (discussing Kumho).

18. Daubert, 509 U.S. at 587; see Graham, supra note 17, at 318–19 (discussing Daubert).

19. See United States v. Hermanek, 289 F.3d 1076, 1094 (9th Cir. 2002) (describing the court’s

gatekeeping function); see also S

TRENGTHENING FORENSIC SCIENCE, supra note 6, at 90–92

(discussing Daubert and Kumho); Bernstein, Expert Witnesses, supra note 16, at 467–72 (describing

development of courts’ gatekeeping role); Capra, The Daubert Puzzle, supra note 16, at 720–23

(discussing gatekeeping role established by Daubert); Jennifer Laser, Comment, Inconsistent

Gatekeeping in Federal Courts: Application of Daubert v. Merrell Dow Pharmaceuticals, Inc. to

Nonscientific Expert Testimony, 30 L

OY. L.A. L. REV. 1379 (1997) (discussing Daubert before

Kumho was decided). The rule is arguably applied differently in criminal cases. Moreno, supra note

5, at 14–18 (suggesting that Daubert has had far less impact in criminal cases).

20. See Tassin v. Sears, Roebuck & Co., 946 F. Supp. 1241, 1246–48 (M.D. La. 1996)

(discussing debate and citing cases); see also Walter G. Amstutz & Bobby Marzine Harges,

Evolution of Controversy: The Daubert Dilemma: The Application of Daubert v. Merrell Dow

Pharmaceuticals Inc. to Expert Testimony of Law Enforcement Officers in Narcotics-Related Cases,

23 U.

HAW. L. REV. 67, 78–84 (2000) (discussing debate); Erica Beecher-Monas, Blinded by

Science: How Judges Avoid the Science in Scientific Evidence, 71 T

EMP. L. REV. 55, 80 (1998)

(discussing disagreement concerning which types of evidence are subject to Daubert analysis);

Capra, The Daubert Puzzle, supra note 16, at 738–51 (discussing applicability of Daubert to non-

scientific expert opinion); K. Issac deVyver, Comment, Opening the Door but Keeping the Lights

Off: Kumho Tire Co. v. Carmichael and the Applicability of the Daubert Test to Nonscientific

Evidence, 50 C

ASE W. RES. L. REV. 177, 183–85 (1999) (explaining the strong disagreement among

circuits, judges, and legal commentators about the scope of Daubert and its applicability to

nonscientific evidence); Laser, supra note 19, at 1389 (discussing debate).

21. See F

ED. R. EVID. 702 advisory committee’s note (recognizing courts’ gatekeeper role); see

also Capra, Distinguishing Between Lay Witnesses, supra note 3, at 34 (discussing courts’

gatekeeping role for expert and lay opinion prior to amendment of rules).

22. See F

ED. R. EVID. 702 advisory committee’s note (recognizing the importance of assurance

of reliability).

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opinion is presented in a manner that permits the jurors to fairly evaluate it.

In the subsections that follow, this Article outlines the rules governing lay

and expert opinion and defines the line between the two types of opinion.

A. Lay Opinion—Rule 701

Rule 701 governs lay opinion. The rule provides:

If the witness is not testifying as an expert, the witness’[s]

testimony in the form of opinions or inferences is limited to those

opinions or inferences which are (a) rationally based on the

perception of the witness, and (b) helpful to a clear understanding of

the witness’[s] testimony or the determination of a fact in issue, and

within the scope of Rule 702.

The rule defines four hurdles that lay opinion must clear to gain

admission: (1) the witness must speak from personal knowledge; (2) the

inferences reflected in the opinion must be rationally based on that

knowledge; (3) the opinion must be helpful to the jury; and (4) the opinion

cannot be based on scientific, technical, or other specialized knowledge.

Thus, every lay opinion rests on a combination of the witness’s experience

base, information known to the witness, and a process of rational reasoning.

The assurance of reliability lies in these first three requirements. The fourth

requirement was added to the rule in 2000 in an effort to better demark the

line between expert and lay testimony.

The court’s job when ruling on the

admissibility of lay opinion is to ensure that the opinion rests on a base of

personal knowledge and experience and is fairly derived from that base with

everyday reasoning.

Much of the routinely admissible lay testimony combines opinion and

non-opinion testimony, and in many instances, that distinction is

inconsequential.

For example, lay testimony as to someone’s age, size, or

behavior involves both factual observation and opinion, but the court need

not decide which aspects of the testimony are fact and which are opinion.

Such routine lay opinion easily clears the hurdles established by the rule,

23. See FED. R. EVID. 701 advisory committee’s note (stressing that jurors should get sufficient

information to evaluate opinion); see also Capra, The Daubert Puzzle, supra note 16, at 705 (noting

the importance of providing opinion in a form that the trier of fact can evaluate).

24. F

ED. R. EVID. 701.

25. Id.

26. See F

ED. R. EVID. 701 advisory committee’s note.

27. See generally Asplundh Mfg. Div. v. Benton Harbor Eng’g, 57 F.3d 1190, 1195–96 (3d Cir.

1995) (discussing the common law rule and criticism and development of federal rule); 1 B

ROUN ET

., supra note 3, § 11, at 53 (discussing Wigmore).

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provided the witness speaks with personal knowledge or does not draw a

patently unwarranted inference.

However, lay opinion is not always so routine. A witness with unusual

experience may be permitted to testify to a lay opinion based on that

experience.

The concern with admitting lay opinion increases when the

opinion goes beyond routine information and expresses a more sophisticated

judgment pertinent to the case. If the court does not assure that the lay

opinion satisfies the requirements of the rule—that the witness has an

adequate basis in personal knowledge and is within the bounds of rational

inference—lay opinion may become a vehicle by which inadmissible

evidence is veiled and then presented to the jury.

Lay opinion that does

not satisfy the rule’s requirements may inject unreliable inferences,

inadmissible hearsay or character evidence, or evidence that would normally

be excluded under Rule 403 as unfairly prejudicial into the testimony.

Careful enforcement of the rule’s requirements should avoid this hazard.

28. United States v. Yazzie, 976 F.2d 1252 (9th Cir. 1992) (discussing admissibility of lay

opinion on question of apparent age). In the Advisory Committee Note to the 2000 amendment of

Rule 701, the committee stated:

The amendment is not intended to affect the “prototypical example[s] of the type of

evidence contemplated by the adoption of Rule 701 relat[ing] to the appearance of

persons or things, identity, the manner of conduct, competency of a person, degrees of

light or darkness, sound, size, weight, distance, and an endless number of items that

cannot be described factually in words apart from inferences.”

ED. R. EVID. 701 advisory committee’s note (quoting Asplundh, 57 F.3d at 1196).

29. See United States v. Williams, 81 F.3d 1434 (7th

Cir. 1996) (allowing former gang member

to decode conversations for the jury); Asplundh, 57 F.3d at 1198–201 (discussing examples); United

States v. Paiva, 892 F.2d 148, 156–57 (1st Cir. 1989) (permitting a drug user to testify as a lay

witness that white powder “looked and tasted” like cocaine, and noting that lay witnesses may testify

to subjects outside “the realm of common knowledge” based on the witness’s individual experience);

see also 1 I

MWINKELRIED ET AL., supra note 10, § 1401, at 604 (suggesting that witnesses with

experience beyond common knowledge may be permitted to testify as lay witnesses rather than

expert witnesses); J

ACK B. WEINSTEIN & MARGARET A. BERGER, WEINSTEIN’S EVIDENCE MANUAL

§ 10.02[2][c], at 10-14 (Joseph M. McLaughlin ed., 2011) (noting that, even after the 2000

amendment to Rule 701, a witness who uses the processes of ordinary persons to form opinions

based on particularized experience and knowledge may testify as a lay witness). But see G. Michael

Fenner, The Daubert Handbook: The Case, Its Essential Dilemma, and Its Progeny, 29 C

REIGHTON

L. REV. 939, 975–77 (1996) (discussing Asplundh); Graham, supra note 17, at 326 n.30 (2000)

(discussing Asplundh and arguing that the experienced witness should be treated as an expert).

30. See, e.g., United States v. Garcia, 413 F.3d 201, 212–13 (2d Cir. 2005) (describing witness’s

reliance on information gathered by other law enforcement agents).

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1. Based on the Perception of the Witness

The lay opinion rule requires that a lay opinion be based “on the

perception of the witness.”

This reflects a particular emphasis on the

personal knowledge requirement that is implicit throughout the Rules of

Evidence.

A witness who rests her opinion on information from others in

addition to her own observations does not comport with the requirements for

lay opinion.

Whereas an expert can rely on vicarious experience and

relayed information, a witness providing lay opinion can call only on

personal experience and personally observed facts.

31. Id. at 211 (emphasis added) (discussing the personal perception requirement). The Second

Circuit emphasized that “lay opinion [is] an acceptable ‘shorthand’ for the ‘rendition of facts that the

witness personally perceived.’” Id. (quoting 4 J

ACK B. WEINSTEIN & MARGARET A. BERGER,

WEINSTEIN’S FEDERAL EVIDENCE § 701.03[1] (Joseph M. McLaughlin ed., 2d ed. 2004)). In

Garcia, the court used the following example of acceptable shorthand:

To illustrate: when an undercover agent participates in a hand-to-hand drug exchange

with a number of persons, the agent may well testify that, in his opinion, a particular

participant, “X,” was the person directing the transaction. Such an opinion is based on

his personal perception of such subjective factors as the respect various participants

showed “X,” their deference to “X” when he spoke, and their consummation of the deal

only upon a subtly signaled approval by “X.” By allowing the agent to state his opinion

as to a person’s role in such circumstances, Rule 701 affords the jury an insight into an

event that was uniquely available to an eyewitness. In this respect, the rule recognizes

the common sense behind the saying that, sometimes, “you had to be there.”

Id. at 211–12; see also Osbourn v. State, 92 S.W.3d 531, 535 (Tex. Crim. App. 2002) (stating that

“perceptions” include the witness’s interpretation of personal sensory experience); 1 B

ROUN ET AL.,

supra note 3, § 11, at 57 n.30 (stating that the perception requirement “mandates that the opinion be

one which a lay person could normally form from observed facts”); 1 I

MWINKELRIED ET AL., supra

note 10, § 1401, at 595 (discussing the perception condition and noting that it refers to the firsthand

knowledge requirement that is codified in Federal Rule of Evidence 602).

32. See Hirst v. Inverness Hotel Corp., 544 F.3d 221, 225–26 (3d Cir. 2008) (discussing and

implementing personal knowledge requirement of Rule 701); United States v. Glenn, 312 F.3d 58,

67 (2d Cir. 2002) (holding that witness lacked basis in personal knowledge to give opinion that

bulge in defendant’s pants, observed from some distance, was caused by a gun); Gorby v. Schneider

Tank Lines, Inc., 741 F.2d 1015 (7th Cir. 1984) (holding that lay opinion was properly excluded

because witness lacked sufficient firsthand knowledge). McCormick emphasizes that the original

common law restriction on lay opinion was based in a concern that the witness not speak without

personal knowledge. 1 B

ROUN ET AL., supra note 3, § 11, at 51–52. Federal Rule of Evidence 602

imposes a personal knowledge requirement on all witnesses except those who testify as experts.

ED. R. EVID. 602.

33. See Garcia, 413 F.3d at 211 (holding lay testimony based on information and opinion

gathered by numerous officers in the course of an investigation to be inadmissible under Rule 701’s

perception requirement); TLT-Babcock, Inc. v. Emerson Elec. Co., 33 F.3d 397, 400 (4th Cir. 1994)

(rejecting lay opinion testimony by a project manager based on reports from his staff); 1 B

ROUN ET

., supra note 3, § 10, at 48 (noting that testimony which rests on statements of others lacks the

requisite firsthand knowledge requirement); 3 G

RAHAM, supra note 5, § 701:1, at 11 n.2 (noting that

a lay witness offering an opinion must base that opinion on the witness’s “own personal

knowledge”).

34. See Garcia, 413 F.3d at 211; Bank of China v. NBM LLC, 359 F.3d 171, 181 (2d Cir. 2004)

(noting that testimony not based on the witness’s perception should not have been admitted as lay

testimony); Edward J. Imwinkelried, The Taxonomy of Testimony Post-Kumho: Refocusing on the

Bottomlines of Reliability and Necessity, 30 C

UMB. L. REV. 185, 203 (2000) [hereinafter

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2. Rationally Based on the Witness’s Perception

The rule further requires that lay opinion be “rationally based” on the

witness’s perception.

The court’s job when applying this requirement of

the rule is to ensure that the opinion expressed by the witness is one that can

be drawn from the witness’s knowledge base using ordinary reasoning.

the witness’s opinion represents too great a leap from the witness’s

knowledge base, the court should exclude it as not rationally based.

3. Helpful

The rule also requires that a lay opinion be “helpful to a clear

understanding of the witness’[s] testimony or the determination of a fact in

Imwinkelried, Taxonomy of Testimony]. Professor Imwinkelried points out that a key distinction

between expert and lay opinion lies in the permissible basis for the opinion. See generally infra

Section III (discussing significance of difference between lay and expert opinion).

35. F

ED. R. EVID. 701 (emphasis added). In United States v. Figueroa-Lopez, 125 F.3d 1241,

1246 (9th

Cir. 1997), the Ninth Circuit assumed that scrutiny under the lay opinion rule was limited

to an assurance that the witness had observed the facts—“mere percipience”—and overlooked the

requirement that the opinion be rationally based on the witness’s perception.

36. The Advisory Committee Note to the 2000 amendment states:

The amendment incorporates the distinctions set forth in State v. Brown, 836 S.W.2d

530, 549 (1992), a case involving former Tennessee Rule of Evidence 701, a rule that

precluded lay witness testimony based on “special knowledge.” In Brown, the court

declared that the distinction between lay and expert witness testimony is that lay

testimony “results from a process of reasoning familiar in everyday life,” while expert

testimony “results from a process of reasoning which can be mastered only by specialists

in the field.”

ED. R. EVID. 701 advisory committee’s note; see also United States v. Kaplan, 490 F.3d 110, 119

(2d Cir. 2007) (noting that courts should ensure that opinion is rationally derived from witness’s

observation); Asplundh Mfg. Div. v. Benton Harbor Eng’g, 57 F.3d 1190, 1201 (3d Cir. 1995)

(emphasizing role of requirement that lay opinion be rationally based on witness’s perception).

Some commentators ascribe no independent significance to the rational relation requirement, but

simply treat it as part of the personal knowledge requirement. See 1 I

MWINKELRIED ET AL., supra

note 10, § 1401, at 595 (discussing requirements for admissibility of lay opinion); see also Bigelow,

supra note 3,

at 4–5 (discussing Asplundh); Capra, Distinguishing Between Lay Witnesses, supra

note 3, at 34 (discussing Asplundh and characterizing this approach as injecting the Daubert

gatekeeping function into Rule 701).

37. Professor Imwinkelried captured this notion in his discussion of how a court should

approach the testimony of a witness who offers an opinion regarding habit. Imwinkelried, The Next

Step, supra note 11, at 2293–94. Professor Imwinkelried suggested that the trial judge can assess the

similarity of the observed behavior that provides the basis for the witness’s opinion on habit. Id. at

2294 (“If the judge’s common sense and intuition tell her that the experiences are not at all parallel,

the inference is acceptable neither as a matter of law nor as a matter of epistemology.”). Thus, he

called for the judge’s assessment that the opinion can be rationally derived from the witness’s

experience/personal knowledge base. Id.

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issue.”

In some cases, the witness uses lay opinion to express information

that cannot be conveyed through a bare factual account.

Even when the

witness can convey the facts without providing opinion testimony, lay

opinion may enrich understanding by adding depth and clarity to the

witness’s account.

Nevertheless, an opinion is not helpful if it simply tells the jury what

inferences to draw

or summarizes the party’s case.

The concern that the

witness threatens the province of the fact finder may likewise lead to the

conclusion that the opinion is not helpful.

For example, a witness who

opines that the defendant was a partner in a drug distribution, based on the

witness’s conclusions from recorded phone calls and other information

gathered in a criminal investigation, supplants the jury’s function of

determining the defendant’s culpability.

Similarly, if the witness’s opinion merely applies everyday reasoning to

evidence equally available to the jury, the court may deem the opinion

unhelpful. For example, if the witness simply compares the defendant’s

appearance with a surveillance photo and opines that the defendant is the

person in the photograph, the court may reject the testimony as unhelpful

because the witness is no better equipped than the jury to draw that

conclusion.

38. FED. R. EVID. 701(b); see also 1 BROUN ET AL., supra note 3, § 11, at 55 (suggesting that

“value to the jury” is the “principal test” under the Rules); 1 I

MWINKELRIED ET AL., supra note 10, §

1401, at 595–96 (discussing helpfulness assessment).

39. Virgin Islands v. Knight, 989 F.2d 619, 629–30 (3d Cir. 1993) (concluding that the trial

court should not have excluded eyewitness testimony that a gun was fired accidentally, even though

it was “difficult . . . to articulate all of the factors that lead one to conclude a person did not intend to

fire a gun,” because the eyewitness testimony would have been helpful to the jury).

40. Id. at 630.

41. United States v. Grinage, 390 F.3d 746, 749–51 (2d Cir. 2004) (holding that lay opinion

testimony admitted at trial was improper because it merely told the jury what result to reach); see

also 1 B

ROUN ET AL., supra note 3, § 12, at 61 n.12 (citing cases rejecting lay opinion on ultimate

issue as unhelpful).

42. United States v. Garcia, 413 F.3d 201, 213–14 (2d Cir. 2005) (holding case agent’s summary

of the evidence in the case is not an admissible, helpful lay opinion). The Garcia court noted that

the agent’s summary replicated the role of the prosecution’s opening statement. Id. But see

Bigelow, supra note 3,

at 5–8 (discussing use of summary witnesses).

43. See, e.g., United States v. Meises, 645 F.3d 5, 18 (1st Cir. 2011) (concluding agent’s

testimony was not helpful because it usurped the role of the jury); Garcia, 413 F.3d at 210–11

(emphasizing the need to protect the province of the jury, and the role of Rule 701’s foundation

requirements in protecting that province); Grinage, 390 F.3d at 750 (noting that agent’s testimony

concerning phone calls usurped the jury’s function); United States v. LaPierre, 998 F.2d 1460, 1465

(9th

Cir. 1993) (expressing concern that testimony may have invaded province of jury); Hand, supra

note 11, at 52.

44. See Garcia, 413 F.3d at 210–11.

45. See discussion infra Section III. For example, an expert can express an opinion that a non-

expert would not be permitted to draw. The expert can base that opinion on information that has not

been admitted, and is even inadmissible. See LaPierre, 998 F.2d at 1465 (holding that police officer

should not have been permitted to give lay opinion that defendant was same person as person in

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4. Not Based on Scientific, Technical, or Other Specialized

Knowledge

In 2000, Rule 701 was amended to stipulate that lay opinion must not be

based on scientific, technical or other specialized knowledge. The

amendment was intended to harden the division between lay opinion and

expert opinion, and to ensure that all opinion based on scientific, technical or

other specialized knowledge would be subject to the reliability requirements

of Rule 702.

This aspect of the Rules is discussed further in the sections

that follow.

B. Expert Testimony—Rule 702

The Federal Rules of Evidence permit expert witnesses to testify in

ways that non-expert witnesses cannot.

Before the court accords a witness

that latitude, it must ensure that the witness satisfies the requirements of

Rule 702.

Rule 702 provides:

If scientific, technical, or other specialized knowledge will assist the

trier of fact to understand the evidence or to determine a fact in

issue, a witness qualified as an expert by knowledge, skill,

experience, training, or education, may testify thereto in the form of

an opinion or otherwise, if (1) the testimony is based upon sufficient

facts or data, (2) the testimony is the product of reliable principles

photograph). But see United States v. Martin, 262 F. App’x 392 (3d Cir. 2008) (allowing similar lay

opinion testimony); Rita, supra note 13, at 64 (concluding that lay witness can sometimes testify

concerning identity of person in photo).

46. The Advisory Committee Notes to the 2000 amendment comment that “Rule 701 has been

amended to eliminate the risk that the reliability requirements set forth in Rule 702 will be evaded

through the simple expedient of proffering an expert in lay witness clothing.” F

ED. R. EVID. 701

advisory committee’s note; see also Hirst v. Inverness Hotel Corp., 544 F.3d 221, 227–28 (3d Cir.

2008) (discussing purpose of amendment); Tampa Bay Shipbuilding & Repair Co. v. Cedar

Shipping Co., 320 F.3d 1213, 1222 (11th Cir. 2003) (commenting that the amendment to Rule 701

was intended to eliminate uses of Rule 701 to avoid reliability requirements of Rule 702); see also

Capra, Distinguishing Between Lay Witnesses, supra note 3, at 34 (discussing reasons for

amendment of Rule 701).

47. See F

ED. R. EVID. 702–03. As the comment to the Rules reflects, expert witnesses can also

provide helpful non-opinion testimony. F

ED. R. EVID. 702 advisory committee’s note (noting

additional role of expert beyond mere opinion testimony); see also John William Strong, Language

and Logic in Expert Testimony: Limiting Expert Testimony by Restrictions of Function, Reliability,

and Form, 71 O

R. L. REV. 349, 360 (1992) (describing possible roles expert may play).

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and methods, and (3) the witness has applied the principles and

methods reliably to the facts of the case.

The rule as originally drafted demanded only that the expert’s testimony

“assist” the trier of fact.

While the expert’s testimony still need not be

necessary to the resolution of the case in order to be admissible,

the rule

now also requires assurance that the testimony is reliable. The 2000

amendment to Rule 702 incorporated the three specific requirements

intended to assure the reliability of expert testimony—the requirements of

sufficient facts or data; reliable principles and methods; and reliable

application.

The amendment contemplates that the expert has employed reliable

methodology—something beyond everyday reasoning—to draw inferences

from the information base.

A number of pre-amendment decisions clarify

the requirements for expert testimony. Both Daubert and Kumho Tire

addressed the question of what qualifies as knowledge and stressed the role

of methodology.

In Daubert, the Court asked what qualified as “scientific

knowledge” admissible as expert testimony under the pre-amendment

rules.

The Court concluded that the way in which “knowledge” was

derived was critical to whether it qualified as “scientific knowledge.”

48. FED. R. EVID. 702.

49. F

ED. R. EVID. 702 advisory committee’s note.

50. 1 I

MWINKELRIED ET AL., supra note 10, § 1404, at 612–13 (discussing Rule 702’s

requirement that expert testimony “assist the trier of fact,” and noting that the standard is more

liberal than the common law, which often required that the subject of expert testimony be “beyond

the comprehension of a layman”); Strong, supra note 47, at 354, 356 (discussing requirements).

51. F

ED. R. EVID. 702.

52. See LifeWise Master Funding v. Telebank, 374 F.3d 917, 928–29 (10th Cir. 2004) (applying

criteria and concluding that witness did not satisfy requirements of rule); see also Brian Leiter, The

Epistemology of Admissibility: Why Even Good Philosophy of Science Would Not Make for Good

Philosophy of Evidence, 1997 BYU

L. REV. 803, 815–17 (discussing limitations of judges as arbiters

of scientific reliability); Strong, supra note 47, at 354–56 (emphasizing role of expert in providing

reliable information both as a “check on jury notice of unreliable propositions” and as a source of

“evaluational or computational accuracy” beyond the jury’s capability).

53. Neither Daubert nor Kumho involved arguable lay opinion; both decisions addressed only

the reliability requirements for expert testimony. See Kumho Tire Co. v. Carmichael, 526 U.S. 137,

153 (1999); Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579, 589, 597 (1993).

54. Daubert, 509 U.S. at 584–85.

55. Id. at 590. The Court explained:

The adjective “scientific” implies a grounding in the methods and procedures of science.

Similarly, the word “knowledge” connotes more than subjective belief or unsupported

speculation. The term “applies to any body of known facts or to any body of ideas

inferred from such facts or accepted as truths on good grounds.” Of course, it would be

unreasonable to conclude that the subject of scientific testimony must be “known” to a

certainty; arguably, there are no certainties in science. But, in order to qualify as

“scientific knowledge,” an inference or assertion must be derived by the scientific

method. Proposed testimony must be supported by appropriate validation—i.e., “good

grounds,” based on what is known. In short, the requirement that an expert’s testimony

pertain to “scientific knowledge” establishes a standard of evidentiary reliability.

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Kumho Tire, the Court recognized that an expert’s experience can play a role

in the testimony.

The Court further emphasized that the experience of the

discipline may play a role in establishing the reliability of expert

testimony.

In addition, of course, the witness must qualify as an expert. To do so,

the witness must possess scientific, technical or other specialized

knowledge. The threshold for expertise was traditionally low.

The

addition of the three reliability factors may have also increased the

requirements to qualify as an expert.

Under the amended rule, the expert

witness must now be competent to apply reliable principles and methods and

to do so reliably.

It will not be enough for the witness merely to have

some knowledge beyond that of the average juror.

Id. (citations omitted).

56. Kumho Tire, 526 U.S. at 148–49. The Court explained:

[W]hether the specific expert testimony focuses upon specialized observations, the

specialized translation of those observations into theory, a specialized theory itself, or the

application of such a theory in a particular case, the expert’s testimony often will rest

“upon an experience confessedly foreign in kind to [the jury’s] own.” The trial judge’s

effort to assure that the specialized testimony is reliable and relevant can help the jury

evaluate that foreign experience, whether the testimony reflects scientific, technical, or

other specialized knowledge.

Id. at 149 (quoting Hand, supra note 11, at 54).

57. The Court stated: “And where such testimony’s factual basis, data, principles, methods, or

their application are called sufficiently into question, the trial judge must determine whether the

testimony has ‘a reliable basis in the knowledge and experience of [the relevant] discipline.’” Id.

(quoting Daubert, 509 U.S. at 592).

58. The Advisory Committee’s Note to Rule 702 states:

The rule is broadly phrased. The fields of knowledge which may be drawn upon are not

limited merely to the “scientific” and “technical” but extend to all “specialized”

knowledge. Similarly, the expert is viewed, not in a narrow sense, but as a person

qualified by “knowledge, skill, experience, training or education.” Thus within the scope

of the rule are not only experts in the strictest sense of the word, e.g. physicians,

physicists, and architects, but also the large group sometimes called “skilled” witnesses,

such as bankers or landowners testifying to land values.

ED. R. EVID. 702 advisory committee’s note; see also United States v. Velasquez, 64 F.3d 844, 849

(3d Cir. 1995) (applying traditional low standard); Miller v. Brass Rail Tavern, Inc., 664 A.2d 525,

528 (Pa. 1995) (stating that the standard for qualification of expert witness is liberal, and stating that

the test is whether the witness has “any reasonable pretension to specialized knowledge on the

subject”); 1 B

ROUN ET AL., supra note 3, § 13, at 86; 2 WIGMORE, supra note 10, § 556, at 751.

59. McCormick cites “an incipient trend to toughen standards” in jurisdictions that have adopted

Daubert. 1 B

ROUN ET AL., supra note 3, § 13, at 71; see also LifeWise Master Funding v. Telebank,

374 F.3d 917, 928–29 (10th Cir. 2004) (requiring qualifications that equip witness to satisfy

reliability requirements); Moreno, supra note 5, at 12–14

(discussing amendment).

60. See F

ED. R. EVID. 702.

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C. Delineating the Difference

The comments to the Rules acknowledge that a witness with a deep

experience base may provide a lay opinion,

and also that a witness may

qualify to give expert opinion solely through experience.

Thus,

experience-based opinion may fall under either Rule 701 or Rule 702. When

a party seeks to elicit opinion testimony based on experience, the court must

determine which rule applies.

The line between lay and expert opinion has never been clearly drawn.

Traditionally, there has always been an area of overlap between the two.

61. The Advisory Committee Note to the 2000 amendment of Rule 701 remarks:

[M]ost courts have permitted the owner or officer of a business to testify to the value or

projected profits of the business[,] without the necessity of qualifying the witness as an

accountant, appraiser, or similar expert. Such opinion testimony is admitted not because

of experience, training or specialized knowledge within the realm of an expert, but

because of the particularized knowledge that the witness has by virtue of his or her

position in the business. The amendment does not purport to change this analysis.

Similarly, courts have permitted lay witnesses to testify that a substance appeared to be a

narcotic, so long as a foundation of familiarity with the substance is established. Such

testimony is not based on specialized knowledge within the scope of Rule 702, but rather

is based upon a layperson’s personal knowledge.

ED. R. EVID. 701 advisory committee’s note (citations omitted).

62. See F

ED. R. EVID. 702 advisory committee’s note. The Advisory Committee Note to the

2000 amendment of Rule 702 states:

Nothing in this amendment is intended to suggest that experience alone—or experience in

conjunction with other knowledge, skill, training or education—may not provide a

sufficient foundation for expert testimony. To the contrary, the text of Rule 702

expressly contemplates that an expert may be qualified on the basis of experience. In

certain fields, experience is the predominant, if not sole, basis for a great deal of reliable

expert testimony.

Id. See, e.g., United States v. Jones, 107 F.3d 1147 (6th Cir. 1997) (no abuse of discretion in

admitting the testimony of a handwriting examiner who had years of practical experience and

extensive training, and who explained his methodology in detail); Tassin v. Sears, Roebuck & Co.,

946 F. Supp. 1241, 1248 (M.D. La. 1996) (design engineer’s testimony can be admissible when the

expert’s opinions “are based on facts, a reasonable investigation, and traditional

technical/mechanical expertise, and he provides a reasonable link between the information and

procedures he uses and the conclusions he reaches”); see also Kumho Tire, 526 U.S. at 156 (stating

that “no one denies that an expert might draw a conclusion from a set of observations based on

extensive and specialized experience”).

63. See, e.g., United States v. Paiva, 892 F.2d 148, 159 (1st Cir. 1989) (noting that the Federal

Rules blurred distinctions between lay and expert opinion); Farner v. Paccar, Inc., 562 F.2d 518,

528–29 (8th Cir. 1977) (concluding that witness with extensive experience could provide either lay

or expert opinion); see also United States v. Horn, 185 F. Supp. 2d 530 (D. Md. 2002) (discussing

line between lay and expert opinion in relation to horizontal gaze nystagmus test); State v.

Blackwell, 971 A.2d 296, 303–05 (Md. 2009) (discussing same).

It is worth noting that the line does not depend on categorization of the witness. The same

witness may provide some testimony as an expert and other testimony as a lay witness. See United

States v. White, 492 F.3d 380, 403 (6th Cir. 2007) (commenting that the Rules “distinguish between

lay and expert testimony, not witnesses”); United States v. Ayala-Pizarro, 407 F.3d 25, 28 (1st Cir.

2005); Downeast Ventures, Ltd. v. Wash. Cnty., 450 F. Supp. 2d 106, 110–11 (D. Me. 2006);

Falconer v. Penn Mar., Inc., 421 F. Supp. 2d 190, 208 (D. Me. 2006). Moreover, the fact that the

witness could qualify as an expert does not foreclose the witness from giving lay opinion testimony.

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However, when the Federal Rules were amended to define the lay-expert

line more clearly and to subject expert opinion to reliability testing,

delineating the difference between the two categories of opinion became

critical. The amendments raised the bar for expert testimony, while also

seeking to eliminate the risk that expert opinion would fly under that

reliability radar and be admitted as lay opinion.

The Rules define the key

question as whether the opinion rests on scientific, technical, or other

specialized knowledge.

Evaluating opinion testimony based on experience raises particular

questions: What constitutes the “specialized knowledge” that requires an

opinion to be handled as expert testimony under Rule 702 and what level of

special background or experience base is consistent with providing lay

opinion under Rule 701? Does the knowledge derived from an especially

rich experience base constitute “specialized knowledge” that forces the court

to evaluate the evidence under the reliability requirements of Rule 702? The

courts must differentiate between a lay opinion that rests on an unusually

rich experience base and an expert opinion based on experience. The courts

should not categorize an opinion as expert merely because the witness

See Teen-Ed, Inc. v. Kimball Int’l, Inc., 620 F.2d 399, 403 (3d Cir. 1980) (fact that accountant-

witness might have qualified as expert did not prevent witness from giving lay opinion concerning

lost profits). Thus, whether a given opinion is lay or expert depends on the basis and development of

the particular opinion.

64. 1 I

MWINKELRIED ET AL., supra note 10, § 1401, at 603–04 (discussing overlap); Capra, The

Daubert Puzzle,

supra note 16, at 768 (summarizing courts’ approach to overlap).

65. F

ED. R. EVID. 702 advisory committee’s note; see also United States v. Garcia, 413 F.3d

201, 215 (2d Cir. 2005) (“The purpose of this final foundation requirement is to prevent a party from

conflating expert and lay opinion testimony thereby conferring an aura of expertise on a witness

without satisfying the reliability standard for expert testimony . . . .”); Bank of China v. NBM LLC,

359 F.3d 171, 181 (2d Cir. 2004) (quoting Advisory Committee Note that amendment of Rule 701 is

intended “to eliminate the risk that the reliability requirements set forth in Rule 702 will be evaded

through the simple expedient of proffering an expert in lay witness clothing” and concluding that the

trial court had improperly allowed that to happen); Falconer, 421 F. Supp. 2d at 208 (“The

amendments to Rule 701 were designed to prevent ‘proffering an expert in lay witness clothing.’”); 4

EINSTEIN & BERGER, supra note 31, § 701.03[4][b], at 701-30 (explaining that “[t]he purposes of

the amendment are twofold. First, it ensures that evidence qualifying as expert testimony under Rule

702 will not evade the reliability scrutiny mandated by the Supreme Court’s Daubert decision and

the 2000 amendment to Rule 702 . . . . Second, it also provides assurance that parties will not use

Rule 701 to evade the expert witness pretrial disclosure requirements of Federal Rule of Civil

Procedure 26 and Federal Rule of Criminal Procedure 16.” (footnotes omitted)); Martinez & Arlyn-

Pessin, supra note 3, at 30 (discussing purpose of amendment). Before the Rules were amended to

incorporate the reliability requirements, a debate raged concerning the application of the requirement

to nonscientific evidence. See, e.g., 1 I

MWINKELRIED ET AL., supra note 10, § 1401, at 604–05

(discussing amendment); Imwinkelried, The Next Step, supra note 11, at 2283–90 (discussing

application of Daubert factors to nonscientific expert testimony).

66. See F

ED. R. EVID. 702.

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possesses an unusual level of experience. Only the application of a reliable

methodology—a proven analytical approach beyond mere everyday

reasoning—should qualify an opinion as expert rather than lay.

III. T

HE LINE BETWEEN LAY AND EXPERT OPINION:

HY DOES IT MATTER?

Each type of opinion offers advantages and disadvantages to the

proponent.

The key differences are explored below. Section A examines

the way in which courts should approach opinion testimony depending on

whether it is lay or expert. Section B considers the difference in the factual

basis required for each type of opinion. Section C discusses the information

required to be disclosed to the court and the jury. Section D focuses on the

form of the opinion testimony. Section E describes the pretrial discovery

obligation that attaches to expert opinion and not to lay opinion. Finally,

Section F notes the deference accorded expert opinion.

A. Evaluation of the Opinion

The two types of opinion require quite different judicial scrutiny. The

court’s competence to scrutinize lay opinion is greater because it rests on

ordinary reasoning and not on the application of a specialized methodology.

For lay opinion, the trial court must ensure that the opinion is helpful to the

jury and reflects reasonable inferences. To do so, the court must determine

whether the witness could fairly draw the inferences by applying everyday

reasoning to the facts the witness knows in the case and the witness’s

experience base.

In contrast, if the witness offers expert opinion, the court must scrutinize

the witness’s claim to reliability by evaluating the methodology, the

sufficiency of the basis, and the application of the methodology. The court

must also determine whether the expert opinion will assist the jury. Thus,

while the court does not need to rise to the level of the expert and is not

invited to assess the reasonableness of the specific inferences, it must check

that the parameters assuring reliability are met.

67. See Samuel R. Gross & Jennifer L. Mnookin, Expert Information and Expert Evidence: A

Preliminary Taxonomy, 34 S

ETON HALL L. REV. 141, 146–47 (2003) (discussing the requirement of

validity and suggesting that the question is whether those in the field of expertise have the tools to

produce valid answers).

68. See 1 I

MWINKELRIED ET AL., supra note 10, § 1401, at 604 (noting the consequences of

classification of opinion).

69. See Amstutz & Harges, supra note 20, at 80 (“The ‘gatekeeper’ function finds description in

Daubert, but it finds its source in Rule 702. Rule 702 makes the trial judge no less the gatekeeper

when counsel characterizes proffered expert testimony as ‘technical’ or ‘specialized,’ rather than

‘scientific.’” (quoting United States v. Webb, 115 F.3d 711, 717 (9th Cir. 1997) (Jenkins, J.,

concurring))); Beecher-Monas, supra note 20, at 65 (“The most important mandate of Daubert is

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B. Basis of the Opinion

The requisite basis for the opinion also depends on how the opinion is

classified. Lay opinion must rest on facts observed by the witness. As a

result, the witness testifying to lay opinion cannot consider any information

outside her realm of personal knowledge.

In contrast, an expert witness can base an opinion on information that is

not within her personal knowledge and is not presented in court.

The

expert can base her testimony on data that is conveyed to her rather than

observed by her, if the information is of the type relied upon by experts in

the particular field.

Further, the information need not be admitted and may

form the basis of the opinion even if it is not admissible.

For example, a

physician testifying about the permanence of the plaintiff’s injury may rely

on the results of tests that are not admitted in evidence.

Thus, an expert

that judges must actively evaluate proposed expert testimony.”); Capra, The Daubert Puzzle, supra

note 16, at 735–38 (noting that the judge need not become a super-expert); Jeffrey M. Schumm,

Precious Little Guidance to the “Gatekeepers” Regarding Admissibility of Nonscientific Evidence:

An Analysis of Kumho Tire Co. v. Carmichael, 27 F

LA. ST. U. L. REV. 865, 865–66 (2000) (arguing

that as gatekeepers, federal judges may assess reliability as they see fit); Laser, supra note 19, at

1411 (noting the benefits of the court’s gatekeeping role, particularly the relief it offers the jury from

“weighing the credibility of highly specialized expert evidence,” and opining that because judges

must examine a witness’s methodology, expert witnesses will not be able to testify based only on

their credentials); Note, Reliable Evaluation of Expert Testimony, 116 H

ARV. L. REV. 2142, 2146

(2003) (explaining how the gatekeeping role of the courts has grown between Daubert and Kumho).

The Supreme Court emphasized that, as gatekeepers, judges must examine “the particular

circumstances of each case to determine whether the factors are reasonable measures of reliability.”

Schumm, supra, at 873 (citing Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579 (1993)). The

gatekeeping role of the judge, if “overly restrictive,” may negatively affect the role of the jury,

especially when the expert testimony is nonscientific. Id. at 890–91 (noting that, because the

reliability of nonscientific expert testimony is not externally tested, the jury is “just as qualified” as

the judge to evaluate, and warning that a rigorous application of the gatekeeping function by the

judge may lead to the judge taking on the role of the jury). The gatekeeping function “should not

expand the trial judge’s role, but rather assist the jury in fulfilling its responsibility.” Id. at 891.

70. See United States v. Freeman, 498 F.3d 893, 905 (9th

Cir. 2007) (pointing out that lay

opinion could not rest on facts not known to the witness and that lay opinion witness could not

testify to hearsay statements that provided basis for opinion).

71. See F

ED. R. EVID. 703, 705; see also United States v. Mejia, 545 F.3d 179, 197–99 (2d Cir.

2008) (discussing line between permissible and impermissible basis for expert opinion); Fenner,

supra note 29, at 978 (noting that experts can base their opinions on inadmissible evidence whereas

lay witnesses cannot); Gross & Mnookin, supra note 67, at 145–46 (discussing difference in basis).

72. See Fenner, supra note 29, at 978.

73. Id.

74. See 1 B

ROUN ET AL., supra note 3, § 15, at 92 (stating that “an expert may give an opinion

based on facts and data” that are not admissible in evidence if “‘of a type reasonably relied upon by

experts in the particular field’” (quoting F

ED. R. EVID. 703)). The Advisory Committee Note

accompanying Rule 703 comments:

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572

can draw on a wider range of information than a lay witness in the process of

forming an opinion.

C. Disclosure of the Basis to the Court and Jury

The party presenting expert or lay opinion has two disclosure

obligations. First, the party must provide enough information to the court to

persuade it that the opinion is admissible.

Second, the party must present

enough information to the jurors to enable them to understand and evaluate

the opinion. The jury does not necessarily hear all the information provided

to the judge to inform the evidentiary ruling. The extent of the disclosure

obligations to both judge and jury depends on how the opinion is classified.

1. Disclosure to the Court

The proponent of expert testimony must provide extensive information

to the court. When a witness testifies as an expert under Rule 702, the court

has a substantial gatekeeper role.

Before the jury is allowed to hear the

expert testimony, the court must determine that the expert has proper

qualifications, is using a reliable methodology appropriately, and is applying

it to an adequate basis.

This assessment requires the proponent to inform

the court in some detail of the basis of the opinion and the process by which

it was reached.

Without that detailed information, the court cannot

determine whether the expert witness has employed reliable methodology

and applied it reliably to a sufficient basis.

The third source [of facts or data upon which expert opinions are based] contemplated by

the rule consists of presentation of data to the expert outside of court and other than by

his own perception. In this respect the rule is designed to broaden the basis for expert

opinions beyond that current in many jurisdictions and to bring the judicial practice into

line with the practice of the experts themselves when not in court. Thus a physician in

his own practice bases his diagnosis on information from numerous sources and of

considerable variety, including statements by patients and relatives, reports and opinions

from nurses, technicians and other doctors, hospital records, and X rays. . . . His

validation, expertly performed and subject to cross-examination, ought to suffice for

judicial purposes.

ED. R. EVID. 703 advisory committee’s note.

75. See F

ED. R. EVID. 104; Imwinkelried, Evaluating the Reliability, supra note 15, at 30–32

(discussing Rule 104).

76. See F

ED. R. EVID. 702 advisory committee’s note.

77. See F

ED. R. EVID. 702.

78. See F

ED. R. EVID. 705 advisory committee’s note.

79. The Advisory Committee Note accompanying Rule 705 comments:

If a serious question is raised under Rule 702 or 703 as to the admissibility of expert

testimony, disclosure of the underlying facts or data on which opinions are based may, of

course, be needed by the court before deciding whether, and to what extent, the person

should be allowed to testify.

Id.

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In contrast, the proponent of a lay opinion must provide the court with

sufficient information to determine not only that the witness has personal

knowledge of the facts that form the basis for the opinion, but also that the

opinion is rationally related to those facts and that it is helpful to the jury.

Rule 701 directs the judge to assure herself that the witness’s inferences are

reasonably derived from the witness’s personal knowledge using only

ordinary reasoning processes.

The judge cannot make that assessment

without knowing the witness’s knowledge and experience base.

2. Disclosure to the Jury

The jurors do not determine admissibility of evidence. Instead, they

assess its weight, ultimately deciding whether they are persuaded by all the

evidence introduced at trial to find in favor of the party with the burden of

persuasion. As a result, the party offering evidence does not normally

disclose to the jury all the information necessary for the judge to rule on

admissibility. Indeed, some of that information may be inadmissible.

Although the party presenting an expert opinion must provide the court

with extensive information, the party does not ordinarily reveal the basis of

the opinion to the jury. The Rules both exempt and circumscribe the expert

from disclosing the basis of her opinion to the jury. The expert need not tell

the fact finder about the basis for an opinion as a prerequisite to expressing

that opinion.

The proponent may elect to have the witness explain the

basis of the opinion to some degree. However, the Rules limit the extent to

which the expert can relay information on which the opinion is based, but

that has not been admitted, to the jury.

Thus, the jury will often be in the

dark as to aspects of the basis for the expert opinion.

80. United States v. Garcia, 413 F.3d 201, 215 (2d Cir. 2005).

81. F

ED. R. EVID. 104(a) provides: “Preliminary questions concerning the qualification of a

person to be a witness, the existence of a privilege, or the admissibility of evidence shall be

determined by the court . . . . In making its determination it is not bound by the rules of evidence

except those with respect to privileges.” The rule allows the court to consider information that is

neither admitted nor admissible, and therefore is not disclosed to the jury.

82. F

ED. R. EVID. 705 provides: “The expert may testify in terms of opinion or inference and

give reasons therefor without first testifying to the underlying facts or data, unless the court requires

otherwise. The expert may in any event be required to disclose the underlying facts or data on cross-

examination.”

83. Rule 703 was amended in 2000 to provide that “[f]acts or data that are otherwise

inadmissible shall not be disclosed to the jury by the proponent of the opinion or inference unless the

court determines that their probative value in assisting the jury to evaluate the expert’s opinion

substantially outweighs their prejudicial effect.” F

ED. R. EVID. 703; see also Capra, The Daubert

Puzzle, supra note 16, at 774–80 (discussing reasons for limiting disclosure of expert’s basis to jury).

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Rule 701 does not specify whether the basis for a lay opinion must be

disclosed to the jury. However, logic dictates that the proponent must

provide the jury with enough information to allow the jurors to evaluate the

opinion and determine whether everyday reasoning supports the inferences

drawn from the facts observed by the witness. If the jury is not given

sufficient information about the basis for the opinion, the opinion will not be

helpful, since the jury’s only choice will be to take it or leave it. Thus, the

witness should present to the jury the information provided to the court in

support of admitting the lay opinion. The witness can give the jury an

overview of her basis for the opinion or can cite specific facts that support

the opinion.

Correspondingly, if the witness relies on experience, she can

explain that experience to the jury.

D. Form of Testimony: The Hypothetical Question

There may also be differences in the way in which expert and lay

opinion are presented at trial. Traditionally, expert witnesses often gave

their opinion in response to hypothetical questions, a practice that is

permitted under the Rules.

The hypothetical question posits the key facts

of the case to the witness as a hypothetical case and asks the witness to

express an opinion based on those hypothetical facts.

An attorney

questioning a lay witness has less latitude to use a hypothetical.

Some courts have asserted that only expert witnesses are permitted to

answer hypothetical questions.

In some cases, the personal knowledge

requirement for lay opinion forecloses the use of hypothetical questions. For

example, in Certain Underwriters at Lloyd’s, London v. Sinkovich, the

plaintiff sued under an insurance policy covering his boat.

At trial, the

insurance company’s investigator was precluded from testifying as an expert

due to the lack of pretrial notice.

Nevertheless, the trial court permitted the

84. See 1 BROUN ET AL., supra note 3, § 11, at 56 (suggesting that witness should provide as

much concrete information as possible).

85. See id. § 14, at 86–91 (discussing hypothetical questions as a vehicle for presenting expert

opinion).

86. See id. § 14, at 86–87; 31 A

M. JUR. 2D Expert and Opinion Evidence § 77, at 101–02 (2002).

87. See United States v. Henderson, 409 F.3d 1293, 1300 (11th Cir. 2005) (concluding that

witness who was not testifying as an expert should not have been permitted to answer hypothetical

question and emphasizing that the distinction between lay and expert witnesses lies in the ability to

answer hypothetical questions); Teen-Ed, Inc. v. Kimball Int’l, Inc., 620 F.2d 399, 404 (3d Cir.

1980) (stating “[t]he essential difference, however, is that a qualified expert may answer

hypothetical questions” (citing the Advisory Committee Notes accompanying Rule 703)); see also 2

IGMORE, supra note 10, § 679, at 940 (stating that only skilled witnesses may respond to

hypothetical questions); Fenner, supra note 29, at 977 (stating that lay witnesses are generally not

allowed to respond to hypothetical questions).

88. Certain Underwriters at Lloyd’s, London v. Sinkovich, 232 F.3d 200, 201 (4th

Cir. 2000).

89. Id. at 203.

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investigator to respond to hypothetical questions concerning steps the

plaintiff could have taken to mitigate the damage to the insured boat.

The

Fourth Circuit held that the testimony was improper coming from a lay

witness.

There were two problems: first, in answering the question the

witness offered an opinion without personally observing the necessary facts,

and, second, the questioning led the witness into areas where he would have

needed expertise.

The witness had not seen the accident and was not

familiar with the area in which it occurred.

As a result, the testimony went

beyond that permitted under Rule 701.

However, a blanket assertion that lay witnesses cannot answer

hypothetical questions is too sweeping to be accurate. There are instances in

which a hypothetical question can fairly be posed to a lay witness. Suppose,

for example, a witness testifies to the opinion that the deceased had the habit

of stopping at a particular restaurant for breakfast on the way to work every

weekday morning.

The witness could then be asked, “If the deceased left

for work at the usual time on August 2, 2009, what time would the deceased

have arrived at the restaurant?” The question is posed as a hypothetical, but

calls for a conclusion within the witness’s competence and requires no

expertise.

90. Id.

91. Id. at 205–06.

92. Id. at 204.

93. Id.

94. Cf. United States v. Wiseman, 339 F. App’x 196 (3d Cir. 2009). In Wiseman, the trial court

permitted an underwriting manager to respond to a series of hypothetical questions even though she

had not been identified as an expert. Id. at 198. The court described the questioning as follows:

The Government solicited Beck’s opinion concerning what she would have done if she

had been presented with a loan application with similar representations of sale price and

present value. The Government asked: “Now, if you had all this information as indicated

in this chart, that you had done if you were associated with both of these loans and had

this information, what would you do with that loan?” The Government later continued:

“Now, let’s assume that as an underwriter or bank employee you have this information in

front of you. What, if anything, do you [do] with that loan file . . . ?” And concerning

the other property, the Government asked, “Now, I’ll ask you to assume for a moment

that [the property] is in one of the most distressed areas . . . . With that assumption in

mind, what do you do with the . . . loan file?”

Id. The Third Circuit declined to address the propriety of the testimony and held that, if error, it was

harmless. Id. at 199.

95. Federal Rule of Evidence 406 permits a witness to testify concerning habit. See

Imwinkelried, The Next Step, supra note 11, at 2293–94 (noting that before admitting evidence

under Rule 406, the judge must assess whether the witness has observed enough instances of conduct

to reach an opinion as to habit).

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E. Pretrial Disclosure Requirements

The rules of procedure in both civil and criminal cases mandate more

extensive pretrial disclosure for expert witnesses than for other witnesses.

The Rules require each party to designate its expert witnesses and provide

pretrial reports describing their testimony.

In contrast, lay opinion may be

introduced with no advance notice. An undesignated witness may therefore

be limited to lay testimony.

The disclosure obligation has frequently been the focal point of disputes

about the scope of the lay opinion rule. Thus, a party that did not provide

information about an opinion witness to the adverse party before trial may

try to avoid exclusion of the evidence by arguing that the witness is a lay

witness testifying to lay opinion. Conversely, the opposing party will argue

that the opinion is expert opinion and should therefore be excluded to

sanction the failure to comply with the discovery rules.

The advance disclosure concerning expert witnesses protects the

opposing party.

Having received pretrial notice, the opposing party can

prepare to respond to the expert testimony. As a result, courts may be

reluctant to treat opinion from an experienced witness as lay opinion because

it allows the party to circumvent the pretrial disclosure requirement.

However, the application of the rule of evidence should not be driven by

procedural considerations.

96. See FED. R. CRIM. P. 16(a)(1)(G); FED. R. CIV. P. 26(a)(2); Downeast Ventures, Ltd. v.

Wash. Cnty., 450 F. Supp. 2d 106, 111 (D. Me. 2006) (explaining the rationale for the disclosure

requirement: “The Rule and the Scheduling Order are designed to place the opposing party on fair

notice: once the expert’s qualifications and the bases for his opinion are disclosed, the opposing

party possesses the necessary knowledge to consider the potential impact and to decide how to

respond—to evaluate whether to engage in further discovery, such as a deposition, to investigate

whether the technical and scientific basis for the proposed testimony is sound, and to determine

whether to obtain a countervailing expert.”); see also Bigelow, supra note 3,

at 8–10 (discussing the

disclosure requirement); Gregory P. Joseph, Emerging Expert Issues Under the 1993 Disclosure

Amendments to the Federal Rules of Civil Procedure, 164 F.R.D. 97 (1996) (discussing issues raised

by disclosure requirements).

97. Downeast Ventures, 450 F. Supp. 2d at 110–11. Professor Capra makes the point that “[t]he

difference . . . boils down to disclosure obligations.” Capra, Distinguishing Between Lay Witnesses,

supra note 3, at 34.

98. See, e.g., United States v. Hamaker, 455 F.3d 1316, 1330–31 (11th Cir. 2006) (addressing

defendant’s complaint that prosecution witness gave expert testimony without compliance with

disclosure rule); United States v. Ayala-Pizarro, 407 F.3d 25, 27 (1st Cir. 2005); Sinkovich, 232 F.3d

at 203–04 (witness restricted to lay testimony due to lack of pretrial notice); Downeast Ventures, 450

F. Supp. 2d at 110–11 (noting that “prudent counsel will designate such a witness as an expert to

avoid the accusation that he has proffered ‘an expert in lay witness clothing’”); see also Martinez &

Arlyn-Pessin, supra note 3, at 28–29 (discussing the disclosure requirement).

99. See United States v. Maher, 454 F.3d 13, 24 (1st Cir. 2006); United States v. Figueroa-

Lopez, 125 F.3d 1241 (9th Cir. 1997) (prosecution’s use of lay witness rules “subverts the

requirements” of the pretrial discovery rule); Bamberger, supra note 5, at 871–77 (discussing

importance of pretrial disclosure).

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F. Deference Accorded Expert Opinion

A party may obtain the advantage of deference by designating a witness

as an expert and presenting opinion as expert rather than lay opinion. First,

the judge may not subject the witness’s reasoning process to close

consideration.

100

Second, the witness’s opinion may gain enhanced

credibility, giving the opinion testimony more weight in the jurors’ minds.

101

Finally, the party relying on the opinion may invoke the witness’s expert

status in argument, inviting the jury to ascribe greater weight to the

testimony because the witness is an expert.

102

IV. T

HE ROLE OF EXPERIENCE IN ESTABLISHING

THE BASIS FOR OPINION TESTIMONY

The determination of whether an experience-based opinion is lay or

expert has significant consequences, yet categorizing such opinions poses a

particular challenge. Before the 2000 amendments, the line between lay and

expert opinion was less stark. Once a court concluded that a witness, like

Mona Lisa Vito of My Cousin Vinny, had unusual experience, the court

could allow the witness to express an expert opinion drawing on that

experience base without regard to whether the witness possessed a reliable

methodology or applied anything other than ordinary reasoning skills to the

100. See Moreno, supra note 5, at 5–7 (discussing inappropriate use of prosecution experts); Neil

Vidmar & Shari Seidman Diamond, Juries and Expert Evidence, 66 B

ROOK. L. REV. 1121, 1177

(2001) (summarizing studies and concluding that judges are not adept at evaluating expert

testimony).

101. See United States v. Webber, 259 F. App’x 796, 802 (6th Cir. 2008) (noting that the trial

court instructed the jury that an agent had testified as an expert); United States v. Freeman, 498 F.3d

893, 903 (9th

Cir. 2007) (noting weight accorded expert testimony); United States v. Downing, 753

F.2d 1224, 1239 (3d Cir. 1985) (noting that some expert testimony has an “aura of infallibility”);

State v. Blackwell, 971 A.2d 296, 308 (Md. 2009) (noting “aura of certainty” that attached to

officer’s testimony concerning horizontal gaze nystagmus test); Beecher-Monas, supra note 20, at 81

(discussing weight accorded to expert testimony); Moreno, supra note 5, at

8. If the court does not

use the term “expert” to label the witness, the enhancement effect is likely to be contained. See F

ED.

R. EVID. 702 advisory committee’s note (cautioning against instructing the jury that the witness is an

“expert”); Charles Richey, Proposals to Eliminate the Prejudicial Effect of the Use of the Word

“Expert” Under the Federal Rules of Evidence in Criminal and Civil Jury Trials, 154 F.R.D. 537,

559 (1994). But see Vidmar & Diamond, supra note 100, at 1177 (summarizing studies of juror

comprehension and evaluation of expert testimony and concluding that jurors competently assess

expert testimony).

102. See, e.g., United States v. Grinage, 390 F.3d 746, 750 (2d Cir. 2004). In Grinage, the court

noted: “[T]he Government in its rebuttal summation told the jury that ‘the agent has the background

to make interpretations,’ suggesting either expertise, for which he had not been qualified, or

investigative information not before the jury.” Id.

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knowledge base.

103

The amendments hardened the line between the two

types of opinion testimony, raising the question of when experience alone

leads to the type of specialized knowledge that qualifies a witness as an

expert and requiring a different approach to experience-based opinion

testimony.

The amendments to the Rules direct courts’ attention to the reasoning

process employed by a witness in reaching an opinion.

104

The Advisory

Committee’s notes on Federal Rule of Evidence 701 state that “the

distinction between lay and expert witness testimony is that lay testimony

‘results from a process of reasoning familiar in everyday life,’ while expert

testimony ‘results from a process of reasoning which can be mastered only

by specialists in the field.’”

105

Thus, the distinction lies in whether the

witness’s reasoning process entails a reliable methodology beyond everyday

reasoning.

106

A lay witness, however experienced, offers no methodology

beyond ordinary reasoning. An expert is equipped to draw more

sophisticated, yet still reliable, inferences.

107

The crux of expert testimony is

that it presents inferences that are supported through the application of a

reliable methodology.

108

Thus, the witness who relies on experience to

support an expert opinion cannot simply claim insights arrived at by

applying everyday reasoning to that experience base, but must explain the

methodology employed to reach that opinion.

109

An experienced witness

103. See, e.g., United States v. Williams, 81 F.3d 1434 (7th

Cir. 1996) (allowing former gang

member to decode conversations for the jury); United States v. Johnson, 28 F.3d 1487, 1496 (8th

Cir. 1994) (allowing former gang members to testify about the business of drug trafficking). After

Daubert was decided, but before Rule 702 was amended to require a demonstration of reliability for

any expert testimony, courts debated whether experience-based expert testimony was subject to

Daubert analysis at all. See generally Tassin v. Sears, Roebuck & Co., 946 F. Supp. 1241, 1246–48

(M.D. La. 1996) (discussing debate and citing cases).

104. United States v. Garcia, 413 F.3d 201, 215 (2d Cir. 2005). In Garcia, the court noted:

In this case, the government made no attempt to demonstrate that Klemick’s challenged

opinion was informed by reasoning processes familiar to the average person in everyday

life rather than by scientific, technical, or other specialized knowledge. . . . We hold that

the foundation requirements of Rule 701 do not permit a law enforcement agent to testify

to an opinion so based and formed if the agent’s reasoning process depended, in whole or

in part, on his specialized training and experience.

Id. at 216.

105. F

ED. R. EVID. 701 advisory committee’s note (quoting State v. Brown, 836 S.W.2d 530, 549

(Tenn. 1992)).

106. See United States v. White, 492 F.3d 380, 404 (6th Cir. 2007) (emphasizing that witnesses’

opinions were expert opinion because they rested on specialized reasoning process and not on

everyday reasoning).

107. McCormick explains: “The expert has something different to contribute. This is the

power—the knowledge or skill—to draw inferences from the facts which a jury could not draw at all

or as reliably.”

1 BROUN ET AL., supra note 3, § 13, at 67.

108. See generally S

TRENGTHENING FORENSIC SCIENCE, supra note 6, at 113–22 (discussing the

development and validation of new methodology); Laser, supra note 19, at 1418 (discussing

meaning of methodology).

109. The Advisory Committee commented:

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who does not bring such methodology to bear should be subject to the

restrictions of the lay opinion rule.

The question for a court faced with an experience-based opinion is how

the experience informs that opinion. In considering that question and the

implications for admitting experience-based opinion, a court should be

guided by the rules governing the admissibility of similar evidence of

experience.

A. How Experience Informs Lay Opinion: Similar Happenings and Other

Act Evidence

All lay opinion testimony is based on experience. The lay opinion

witness brings life experience to bear on the observed facts and forms an

opinion rationally based on those facts.

110

The witness draws conclusions

based on a background of experiencing similar happenings or events and

If the witness is relying solely or primarily on experience, then the witness must explain

how that experience leads to the conclusion reached, why that experience is a sufficient

basis for the opinion, and how that experience is reliably applied to the facts. The trial

court’s gatekeeping function requires more than simply “taking the expert’s word for it.”

ED. R. EVID. 702 advisory committee’s note; see Daubert v. Merrell Dow Pharm., Inc., 43 F.3d

1311, 1319 (9th Cir. 1995) (“We’ve been presented with only the experts’ qualifications, their

conclusions and their assurances of reliability. Under Daubert, that’s not enough.”). The Advisory

Committee also noted: “The more subjective and controversial the expert’s inquiry, the more likely

the testimony should be excluded as unreliable.” F

ED. R. EVID. 702 advisory committee’s note; see

O’Conner v. Commonwealth Edison Co., 13 F.3d 1090 (7th Cir. 1994) (expert testimony based on a

completely subjective methodology held properly excluded); see also Kumho Tire Co. v.

Carmichael, 526 U.S. 137, 151 (1999) (“[I]t will at times be useful to ask even of a witness whose

expertise is based purely on experience, say, a perfume tester able to distinguish among 140 odors at

a sniff, whether his preparation is of a kind that others in the field would recognize as acceptable.”).

The Advisory Committee cited lower court decisions to support the assertion that experience alone

may be sufficient to qualify a witness as an expert. However, those decisions suggest that expert

testimony must be based on something more than simply experience. For example, in United States

v. Jones, 107 F.3d 1147, 1159–61 (6th Cir. 1997), discussing the admissibility of handwriting

analysis, the court noted that the witness’s expertise was a product of knowledge, skill, education,

and training, as well as experience, and commented further that the witness explained his procedure

to the jury. Similarly, in Tassin v. Sears, Roebuck & Co., 946 F. Supp. 1241, 1248 (M.D. La. 1996),

the expert witness brought far more than experience to his testimony: he had both undergraduate and

master’s degrees in mechanical engineering; he had been employed for nine years by the Louisiana

Productivity Center, working in areas that included product development, quality control, and

manufacturing; he had an additional thirteen years of experience working at various companies in

design engineering; he had served as a consultant in the design of various machines and structures.

His proffered testimony concerning alternative designs was excluded because he had not applied his

methodology to a reliable base of information. Id. at 1250–52.

110. Professor Imwinkelried asserts that “one of the most fundamental tests of the reliability of

nonscientific opinion is whether it has any supporting experience, either personal or vicarious.”

Imwinkelried, The Next Step, supra note 11, at 2291. He goes on to cite Hume’s assertion that “the

trustworthiness of an inference depends upon ‘a repetition of similar’ experiences.” Id.

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applies everyday reasoning informed by that experience to form the

opinion.

111

In order to determine that the opinion is rationally related to the

witness’s knowledge, the court must make sure that the witness has the

experience base, as well as the observed facts, to rationally derive the

opinion.

112

The court should demand that the witness’s experience base include a

sufficient sample of similar events, and that those past events support the

witness’s inferences. Applying these criteria, courts have admitted the

opinions of unusually experienced lay witnesses, as well as the opinions of

witnesses with a more ordinary experience base.

113

But the test is always the

111. See, e.g., Bank of China v. NBM LLC, 359 F.3d 171, 180–81 (2d Cir. 2004) (holding that

the witness who had acquired special knowledge when he conducted an investigation of the bank’s

dealings with the defendant could give lay opinion based on that knowledge, and allowing the

witness to testify concerning business community’s understanding, certain business concepts, and

what constituted fraud in the transactions with which the witness was familiar); United States v.

Jones, 24 F.3d 1177, 1179–80 (9th Cir. 1994) (concluding that the defendant’s voice identification

witness was not an expert because he could point to no reliable methodology supporting his

testimony, but permitting him to testify to his lay opinion based on his aural comparison of the

defendant’s voice with that on recordings introduced by the prosecution). Jurors also bring

experience to bear on the case. See Taylor v. Sisto, 606 F.3d 622 (9th Cir. 2010) (discussing the role

of experience in jurors’ assessments and holding that trial court committed error by instructing

prospective jurors that they would have to set aside all their experiences to serve on the jury);

Strong, supra note 47, at 353.

112. See, e.g., Bank of China, 359 F.3d at 180–81 (holding that the trial court had improperly

permitted the lay witness to testify to some opinions not clearly based on the witness’s perceptions);

O’Conner, 13 F.3d at 1106–07 (holding that the testimony of a physician claiming that he could

recognize radiation-induced cataracts was properly excluded where the expert did not ground his

opinion in the scientific literature and had only observed five cases of radiation induced cataracts).

113. Courts have traditionally permitted property owners or those intimately involved with a

business to provide lay opinion concerning the value of the property or workings of the business.

ED. R. EVID. 701 advisory committee’s note; see, e.g., United States v. Wiseman, 339 F. App’x 196

(3d Cir. 2009) (holding that witnesses experienced in real estate were properly permitted to testify as

lay witnesses concerning loan process); LifeWise Master Funding v. Telebank, 374 F.3d 917, 928–

30 (10th Cir. 2004) (summarizing precedent and holding that company president could have testified

to lost profits using ordinary techniques based on the company’s history, but could not testify to a

model concerning moving averages, compounded growth rates, and S-curves, or other technical,

specialized subjects in which he was not versed); Tampa Bay Shipbuilding & Repair Co. v. Cedar

Shipping Co., 320 F.3d 1213, 1217–18 (11th

Cir. 2003) (concluding that company’s employees

could properly testify as lay witnesses that company’s charges were reasonable); Asplundh Mfg.

Div. v. Benton Harbor Eng’g, 57 F.3d 1190, 1198–99 (3d Cir. 1995) (collecting examples); MCI

Telecomms. Corp. v. Wanzer, 897 F.2d 703, 706 (4th

Cir. 1990) (concluding that bookkeeper should

have been permitted to testify to lay opinion on the question of the profits from leases since she

personally kept the relevant records); Teen-Ed, Inc. v. Kimball Int’l, Inc., 620 F.2d 399 (3d Cir.

1980) (holding that party’s accountant should have been permitted to provide lay opinion concerning

party’s lost profits); Falconer v. Penn Mar., Inc., 421 F. Supp. 2d 190, 208 (D. Me. 2006)

(concluding that witness’s experience in engineering business qualified him to testify as a lay

witness concerning engineering responsibilities); see also 1 B

ROUN ET AL., supra note 3, § 10, at 51

(noting that a lay witness who was familiar with a business’s operation may be permitted to testify

concerning the business’s profits). But see Donlin v. Philips Lighting N. Am. Corp., 564 F.3d 207,

215 (3d Cir. 2009) (concluding that lay witness lacked basis to express opinion concerning estimated

lost earnings and pension benefits); JGR, Inc. v. Thomasville Furniture Indus., Inc., 370 F.3d 519,

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same: whether the witness has enough personal information drawn from

experience and observation to reach the offered conclusion using everyday

reasoning.

Look for a moment at an example of routine lay opinion. Testimony

concerning the speed of a car is often cited as an example of unremarkable

admissible lay opinion.

114

Most adult lay witnesses have a sufficient

experience base driving, riding in, and observing moving vehicles to be able

to draw a rational inference concerning speed. But consider a witness who

has lived her entire life in central Manhattan, does not drive, and has never

seen highway traffic. As an adult, she ventures for the first time into the

countryside and happens to witness a high-speed traffic accident. Should

she be permitted to testify that, in her opinion, the defendant’s car was

moving sixty-five miles per hour? She has no experience base that would

assure the accuracy of her opinion. While possessed of the necessary

personal knowledge of the traffic accident, she does not have the

accumulation of observed similar events necessary to legitimatize her

opinion by assuring that it is rationally based on her knowledge. Her

opinion should be excluded.

115

Lay opinion should not be admitted without

the assurance that the witness has the requisite experience of observing

sufficient similar events to draw accurate inferences.

In some cases, the courts simply fail to apply Rule 701 with care. For

example, in United States v. Simas,

116

the court held that agents had properly

525–26 (6th Cir. 2004) (holding that accountant-witness could not provide lay opinion on lost profits

because he did not have personal knowledge of the plaintiff’s books).

114. See Bandera v. City of Quincy, 344 F.3d 47, 54 (1st Cir. 2003) (listing speed of a vehicle as

an example of the “limited” testimony permitted by Rule 701); Asplundh, 57 F.3d at 1197 (citing

speed of vehicle as quintessential lay opinion testimony); Clifford v. Commonwealth, 7 S.W.3d 371,

374 (Ky. 1999) (describing testimony about the speed of a moving vehicle as common lay opinion

testimony); 3 G

RAHAM, supra note 5, § 701:1, at 26 (including the speed of a vehicle in list of

common topics about which lay witnesses may testify); Imwinkelried, Taxonomy of Testimony,

supra note 34, at 194 (listing the speed of a car as an example of admissible lay opinion testimony).

115. See also 3

GRAHAM, supra note 5, § 701:1, at 13 n.3 (discussing recluse who has no

experience driving or riding in a car and concluding recluse would not be able to testify as to the

observed speed of a car).

116. 937 F.2d 459, 464–65 (9th Cir. 1991); see also United States v. Colón Osorio, 360 F.3d 48,

52–53 (1st Cir. 2004) (permitting officer to give lay opinion that gun possessed by defendant was

manufactured outside Puerto Rico and therefore had traveled in interstate commerce). In Colón, the

witness’s lay opinion masked underlying evidence questions. The court allowed the opinion because

the officer had visited the factory in Massachusetts where the gun was manufactured. Colón, 360

F.3d at 53. The information was “based on information gleaned from [the officer’s] personal

experience . . . and was arrived at ‘from a process of reasoning familiar in everyday life.’” Id. The

officer did not see the gun manufactured, so he was necessarily relying on hearsay rather than his

own knowledge. It seems unlikely that a court would have permitted a non-law enforcement witness

to testify that a particular item was manufactured in a particular location simply on the basis of

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testified as lay witnesses concerning their understanding of certain

ambiguous statements made by the defendant. The court first noted that the

agents had heard the actual statements, and concluded that the personal

knowledge requirement of Rule 701 was therefore satisfied.

117

The court

further concluded that the helpfulness requirement was satisfied simply

because the opinions would help the jury to make sense of the sometimes

incomprehensible statements of the defendant.

118

However, the court failed

to implement the requirement that the opinion be rationally related to the

facts observed by the witness.

119

The court should have required the

prosecution to demonstrate that, in addition to hearing the statements, the

agents had a background that allowed them to interpret those statements,

based on prior similar instances. If that background was lacking, the

opinions were not rationally derived and threatened to mislead the jury. The

court may have assumed that the agents based their interpretation on prior

similar conversations with the defendant, but by failing to articulate that

basis and the need for a rational connection between the opinion and the

observed facts, the court stripped Rule 701 of its intended role.

120

The way in which experience informs lay opinion can be better

understood by looking at other evidence that samples experience as a way of

advancing fact-finding. To understand how courts should approach

experience-based testimony, one should consider how courts approach

evidence of similar happenings and other acts. These types of evidence

require special scrutiny as a prerequisite to admissibility. The same scrutiny

should be applied to lay opinion, which purports to draw inferences from

similar happenings or other acts.

having visited the factory. Courts have also allowed such testimony as expert testimony under Rule

702, although it is not clear how the testimony satisfies the reliability requirements. See United

States v. Cormier, 468 F.3d 63, 72–73 (1st Cir. 2006) (allowing agent to testify as expert regarding

origin of weapon); United States v. Singletary, 268 F.3d 196, 197–98 (3d Cir. 2001) (ATF agent’s

expert testimony regarding origin of weapon sufficient to establish interstate commerce element of

18 U.S.C. § 922(g)). By treating the testimony as expert testimony, the courts allow the prosecution

to employ a witness with no special methodology to rely on records and conversations to state an

opinion, relieving the government of the obligation to obtain primary admissible evidence

concerning a gun’s origin.

117. Simas, 937 F.2d at 464.

118. Id. at 465.

119. Id.

120. See also United States v. Freeman, 498 F.3d 893, 903–05 (9th Cir. 2007) (holding agent’s

testimony interpreting conversations largely admissible as lay opinion); United States v. De Peri,

778 F.2d 963, 977–78 (3d Cir. 1985) (allowing witness to interpret conversations without

considering basis for opinion). In some cases, courts allow this testimony as expert testimony.

Instead, it should be evaluated as lay testimony.

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1. Similar Happenings and Lay Opinion

Events that are not part of the matter on which a trial focuses are not

generally admissible.

121

However, in some instances, such an event has

particular probative value and is admitted as a similar happening. The

analysis of similar happenings evidence provides a model for evaluating lay

opinion.

Admissibility of similar happenings and other events is governed by

Rules 402 and 403.

122

Rule 402 provides that if evidence has probative

value, it is admissible unless otherwise excluded.

123

The probative value of

other events generally turns on questions of similarity.

124

Rule 403 permits

the court to exclude evidence on grounds such as the risk of unfair prejudice,

jury confusion, and waste of time.

125

Similar happenings evidence often

generates one or more of these problems and may be excluded as a result.

While not generally admissible, similar happenings evidence may be

admitted to establish the existence of a defect or dangerous condition or to

prove notice of such a problem.

126

For example, evidence of other auto

accidents at a specific point on a highway may act as evidence that the

stretch of road was defectively designed or constructed. But the other

accidents support that inference only if they happened under substantially

similar conditions. If the case on trial involves a fair weather accident and

the other accidents occurred during inclement weather, then the other

happenings have little probative value in the case on trial. If the court

admits evidence of the other accidents, the jury will apply everyday

reasoning to determine the probative value, but may be confused or unfairly

prejudiced because the other accidents are superficially similar, yet

dissimilar in key respects.

127

Thus, to determine the admissibility of the

similar accidents, the trial court should scrutinize the offered evidence to

determine whether the similarities permit the jury to draw the desired

121. 22 CHARLES ALAN WRIGHT & KENNETH W. GRAHAM, JR., FEDERAL PRACTICE AND

PROCEDURE § 5170, at 111–12 (1978).

122. Id. § 5170, at 116–18; see also Simon v. Town of Kennebunkport, 417 A.2d 982 (Me. 1980)

(discussing use of other accidents to prove defect in sidewalk and applying Rule 402 and 403 to

assess admissibility).

123. F

ED. R. EVID. 402.

124. See 1 B

ROUN ET AL., supra note 3, §§ 196–200, at 788–808 (discussing criteria for admitting

similar happenings and transactions).

125. F

ED. R. EVID. 403.

126. See 1 B

ROUN ET AL., supra note 3, § 200, at 802–04.

127. 22 W

RIGHT & GRAHAM, supra note 121, § 5170, at 114–16.

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inference and whether the evidence will generate too great a risk of unfair

prejudice or confusion.

128

The process of evaluating lay opinion should follow a parallel path. The

court should determine the basis for the opinion—both the perceived facts

relevant to the case and the experience base of similar happenings that the

witness can bring to bear on the issue. The court should then ask whether

everyday reasoning could support drawing the proffered opinion from that

base of knowledge. One possible basis for rejecting the opinion is a

deficiency in the witness’s experience base. If the witness has not observed

enough similar happenings, the witness lacks the basis in personal

experience to draw the opinion.

Consider an example. Suppose the defendant attempts to elicit the lay

opinion that the plaintiff lost control of her car because it was snowing and

she was driving too fast for the conditions. If the witness had only observed

driving in snowy conditions on two prior occasions, the witness would not

have experienced enough similar situations to draw the desired conclusion

about the plaintiff’s driving. Like a jury confronted with improper similar

happenings evidence, the witness may be led to the opinion by superficial

similarity, confusion, or improper reasoning. Even if the witness observed

the entire accident, the witness should not be allowed to express that

opinion.

The lay testimony allowed in Soden v. Freightliner Corp.

129

exemplifies

lay testimony that has a proper experience base. It illustrates the proper

relationship between similar happenings evidence and lay opinion. The

plaintiffs in Soden, Soden’s widow and children, alleged that a design flaw

in step brackets on the defendant’s truck had resulted in the death of Soden

in a fire that erupted after the truck he was driving rolled over.

130

The trial

court permitted a witness with extensive experience servicing trucks to

testify concerning the damage to the fuel tanks he observed on that particular

truck involved in the accident, and also on two or three other trucks

manufactured by the defendant that he had seen following other accidents.

131

The other accidents included one rollover and one or two jackknifes, and

none involved a fire.

132

However, in each of the accidents, the witness had

observed puncture marks in the fuel tank near the location of the step

128. Id. §§ 5213–14, at 258–73.

129. 714 F.2d 498 (5th Cir. 1983).

130. Id. at 500.

131. Id. at 510–11.

132. Id. The witness testified that on the other occasions, he had “seen puncture holes in the fuel

tanks at the location of the step brackets” that were allegedly defective; that he had seen similar

holes in the fuel tanks of the plaintiff’s truck; that the brackets caused the fire and that their design

was dangerous; and that the plaintiff’s accident prompted him to modify the brackets by removing

the pointed ends. Id. On appeal, the defendant challenged only the witness’s opinion testimony on

cause and dangerousness. Id.

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brackets.

133

The accidents were thus sufficiently similar on the issue of the

brackets’ design and the punctures they caused in the accident.

134

The

differences in the way the accidents happened and the absence of fire did not

affect the witness’s ability to infer that the brackets tended to puncture the

fuel tank and were therefore dangerously designed.

135

The evidence of the

similar events could have been admitted, and the lay opinion based on those

events was properly allowed.

136

When a party offers lay opinion, the court should ask whether the other

events on which the witness bases her reasoning satisfy the criteria applied

to similar happenings. The trial court should assess the points of similarity

and difference to determine whether the events in the witness’s prior

experience have sufficient probative value, and determine whether the

differences undermine the probative value or inject confusion. When the

witness’s experience includes enough similar instances to support the

offered opinion, the witness should describe to the jury, at least in summary,

the similar happenings that form the experience base so the jury can then

determine the appropriate weight to accord the opinion. Unfortunately,

courts do not always include this step in their evaluation of lay opinion.

137

2. Other Act Evidence and Lay Opinion

Lay opinion sometimes purports to draw conclusions about an actor’s

behavior based on that actor’s prior conduct. The witness takes what she

knows about the actor and uses that as a basis for interpreting the actor’s

behavior in the context of the case on trial. The courts should approach such

lay opinion cautiously. The law carefully circumscribes the use of character

and other act evidence.

138

Lay opinion based on such evidence should be

subject to the same limitations.

The Federal Rules of Evidence strictly limit the use of a person’s

character or acts at other times as a basis for inferring action at the time in

question.

139

The law generally prohibits proof of character—the type of

person someone is—as a basis for concluding how the person acted at the

133. Id. at 510.

134. Id. at 511–12.

135. Id.

136. Id. at 512.

137. See infra Section VI.C.

138. See F

ED. R. EVID. 404.

139. See id.

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time in question.

140

Other act evidence

141

is restricted because of the risk

that the jury will use this evidence to draw inferences about the character or

conduct of the actor. The chain of inference, either from character to action

in conformity or from other acts to character to action in conformity, is

specifically prohibited by the Federal Rules of Evidence in most instances.

142

Lay opinion regarding an actor based on the actor’s past conduct should be

held to corresponding limitations.

There are two ways an actor’s prior conduct may become admissible at

trial as evidence of the actor’s behavior—as evidence of habit or as the basis

for judging an actor’s character in the limited circumstances in which

character evidence is admissible.

143

The rules governing habit evidence

140. See id.

141. Other act evidence refers to proof of the person’s conduct at some time other than events

that are the subject of the trial.

142. F

ED. R. EVID. 404(b). But see FED. R. EVID. 404(a)(1)–(3), 413–15.

143. Federal Rule of Evidence 404(a) provides that evidence of a person’s character or a trait of

character is admissible for the purpose of proving action in conformity therewith on a particular

occasion in the following limited situations:

(1) Character of Accused. In a criminal case, evidence of a pertinent trait of character

offered by an accused, or by the prosecution to rebut the same, or if evidence of a trait of

character of the alleged victim of the crime is offered by an accused and admitted under

Rule 404(a)(2), evidence of the same trait of character of the accused offered by the

prosecution; (2) Character of Alleged Victim. In a criminal case, and subject to the

limitations imposed by Rule 412, evidence of a pertinent trait of character of the alleged

victim of the crime offered by an accused, or by the prosecution to rebut the same, or

evidence of a character trait of peacefulness of the alleged victim offered by the

prosecution in a homicide case to rebut evidence that the alleged victim was the first

aggressor; (3) Character of Witness. Evidence of the character of a witness, as provided

in Rules 607, 608, and 609.

ED. R. EVID. 404(a)(1)–(3). In those instances, the party may establish character by calling an

opinion witness. See 1 I

MWINKELRIED ET AL., supra note 10, § 804, at 341–51 (describing use of

opinion evidence to establish a defendant’s character). The party may also prove character with

evidence of reputation. F

ED. R. EVID. 405. See 1 IMWINKELRIED ET AL., supra note 10, § 804, at

342–45 (listing and describing the use of reputation evidence in establishing character of defendant).

Reputation represents a more filtered assessment of conduct over time. See 1 B

ROUN ET AL., supra

note 3, § 187, at 746 (describing reputation evidence as the “preferred mode of proof of character”);

1 I

MWINKELRIED ET AL., supra note 10, § 804, at 344 (noting that all courts permit the use of

reputation testimony, and describing such testimony as “likely to be fairly trustworthy”). Also, if

character is an element of a claim or defense, the party can introduce specific instances of conduct to

allow the jury to infer character from past conduct. See 1 B

ROUN ET AL., supra note 3, § 187, at

744–47 (noting that, when character is a material fact in a case, courts typically permit evidence of

specific acts); 1 G

RAHAM, supra note 5, § 405:2, at 919–20 (noting that specific instances of conduct

may be introduced into evidence whenever character is an essential element of a charge, claim, or

defense); 1 I

MWINKELRIED ET AL., supra note 10, § 804, at 344 (stating that evidence of specific acts

are permissible when a defendant’s character is “an ultimate, material fact in the case”). The opinion

regarding the person’s character is based on the witness’s assessment of the person’s past behavior

in light of the witness’s experience of people in general. The character witness must have both a

sufficient sampling of the person’s conduct and sufficient relevant life experience to rationally

support the opinion. See 1 B

ROUN ET AL., supra note 3, § 11, at 57 n.30 (stating that “a foundation

must be laid as to the witness’s personal knowledge of facts to which the observed facts are being

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relate closely to lay opinion. Proof of habit may be admitted to prove

behavior consistent with the actor’s habitual behavior only if evidence of the

actor’s past conduct establishes a pattern so regular and consistent that it

supports an inference about the actor’s behavior at the time in question.

144

Habit may be established one of two ways. The party may prove enough

specific instances of conduct that the jury can fairly infer the behavior was

habitual. Alternatively, the party may present a witness who can testify to

the habit.

145

The witness’s testimony takes the form of lay opinion and

should be assessed accordingly.

146

To arrive at the opinion, the witness

applies ordinary reasoning and knowledge gleaned from experience with

other people to the witness’s observation of the actor. The witness must

have a large enough sampling of the behavior in question to rationally

conclude it is habitual.

147

Thus, when determining whether habit evidence is

admissible, the court must ensure that the instances of similar behavior

presented to the jury or known to the opinion witness support the conclusion

about habit as an indicator of likely conduct at the time in question.

compared”); see also United States v. Williams, 212 F.3d 1305, 1309–10 (D.C. Cir. 2000). In

Williams, the D.C. Circuit noted:

The Office of Legal Education of the Executive Office for United States Attorneys

provides guidelines to establish a proper foundation for the opinion testimony of a skilled

lay observer: 1. That the witness has, on prior occasions sufficient in number to support a

reasonable inference of knowledge of or familiarity with a subject, observed particular

events, conditions, or other matters.

Williams, 212 F.3d at 1309–10 n.6.

144. F

ED. R. EVID. 406 provides:

Evidence of the habit of a person or of the routine practice of an organization, whether

corroborated or not and regardless of the presence of eyewitnesses, is relevant to prove

that the conduct of the person or organization on a particular occasion was in conformity

with the habit or routine practice.

145. See 1 B

ROUN ET AL., supra note 3, § 195, at 786 (listing witness testimony and specific

instances as methods of proving habit, and noting that witness testimony is the most common

method of proof); 1

GRAHAM, supra note 5, § 406:4, at 949 (noting that, while Rule 406 is silent on

the method of proof, the Advisory Committee’s Note to Proposed Rule 406(b) listed opinion

testimony and proof of “specific instances [of conduct] sufficient in number to warrant a finding [of]

habit” as methods of proof); 1 I

MWINKELRIED ET AL., supra note 10, § 809, at 363 (listing specific

instances and opinion evidence as “recognized methods” of proving existence of habit).

146. See 1 G

RAHAM, supra note 5, § 406:4, at 951 (noting that a lay witness may provide

testimony regarding habit, and that such testimony must comply with the provisions of Rule 701); 1

MWINKELRIED ET AL., supra note 10, § 809, at 364 (stating that judges should determine the

admissibility of lay opinion using Rule 701 criteria).

147. See 1 B

ROUN ET AL., supra note 3, § 195, at 786 (noting that there must be enough instances

to establish habit); 1 G

RAHAM, supra note 5, § 406:2, at 940 (stating that habit testimony is

admissible “only if a sufficient pattern of repeated responses is established”).

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Other act evidence may also be admitted if it is relevant for a non-

character, non-conduct purpose.

148

To admit other act evidence on this

basis, the trial court must determine that the evidence plays a non-character

role and will not simply be used as character evidence. Thus, the court has

to assess the connection between the other act evidence and the permissible

inference for which it is offered. Moreover, even if the evidence has

probative value for a non-character purpose, the court has discretion to

exclude the evidence if it is substantially more likely that the jury would use

it as evidence of character and action in conformity than for the permitted

purpose.

149

Thus, other act evidence is subject to strict rules. In the situations in

which such evidence is admissible, the trial court is required to carefully

assess the basis for offering the evidence and its probative value for the

permitted purpose. Opinion testimony based on observation of past conduct

should be similarly scrutinized and restricted.

150

3. Evidence of Third Party Conduct and Lay Opinion

Lay opinion is sometimes derived from assessments based on third party

conduct. The witness takes what she knows about the behavior of others and

uses that as a basis for interpreting or predicting the behavior of the actor in

question. The courts should approach lay opinion that rests on third party

conduct with particular caution. Evidence of third party conduct is rarely

admissible, and lay opinion based on such evidence should likewise be

restricted.

Evidence of a third party’s conduct provides little probative insight into

how someone else acted. Such use of third party conduct raises the concerns

underlying both evidence of similar happenings and evidence of the prior

conduct of the actor. Superficial similarity may draw the witness and the

jury to unfounded inferences. A witness using third party behavior to form

an opinion may over-generalize, reaching unsupported conclusions.

Take a simple example. Suppose the defendant crashes her car into a

tree, injuring a passenger in the car. Suppose also that two other drivers in

the previous six months crashed into the same tree and were shown to have

been negligent. Can the passenger-plaintiff introduce evidence of those

148. Other act evidence may also be admissible when it proves something other than character

and conduct in conformity, such as identity, motive, or knowledge. F

ED. R. EVID. 404(b).

149.

FED. R. EVID. 403 provides: “Although relevant, evidence may be excluded if its probative

value is substantially outweighed by the danger of unfair prejudice, confusion of the issues, or

misleading the jury, or by considerations of undue delay, waste of time, or needless presentation of

cumulative evidence.” See also 1 G

RAHAM, supra note 5, § 404:5, at 607 (discussing Rule 403).

150. Cf. Moreno, supra note 5, at 43–44 (suggesting that drug jargon testimony acts

impermissibly as evidence of bad character by suggesting to the jury that the defendant learned the

jargon while engaged in prior drug dealing).

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crashes and ask the jury to infer that, because those two drivers were

negligent, the defendant was also negligent? The answer is clearly no. If all

three drivers were driving rental cars, could the plaintiff introduce that

evidence and ask the jury to conclude that the plaintiff, having the use of the

rental car in common with the third parties, was therefore negligent? Again,

the answer is a clear no. While evidence of similar accidents may be used to

establish a static condition, such as defect in the design or maintenance of

the road,

151

it cannot be used to prove the behavior of the plaintiff.

Correspondingly, a witness should not be allowed to base a lay opinion that

the defendant was negligent on the conduct or characteristics of the other

two drivers.

That is not to say that third party conduct is never relevant or that a lay

opinion based on third party conduct is never admissible.

152

In some

situations, experience with the behavior of others can appropriately inform a

witness’s lay assessment. For example, the lay opinion that a person acted

intoxicated may be based entirely on the comparison of the person’s conduct

with that of intoxicated third parties observed by the witness at other

times.

153

If the person in question exhibits similar behavior, the witness can

fairly opine that the person was intoxicated.

154

When lay opinion rests in part on third party conduct, the court should

challenge and scrutinize the underlying chain of inferences. The court

should demand a very high level of similarity between the third party

conduct and that of the person in question. The court should also make sure

151. See 1 BROUN ET AL., supra note 3, § 324.3, at 418 (discussing the admissibility of evidence

of similar accidents and injuries and the role the evidence may play).

152. In some cases, courts exclude testimony based on a third party that is relevant and would be

helpful to the jury. In Trevino v. City of Rock Island Police Department, 91 F. Supp. 2d 1204, 1206–

08 (C.D. Ill. 2000), the court rejected the testimony of a monocular police officer on a range of

issues relating to whether a monocular officer could appropriately perform the job of a police officer.

The court held that the witness did not qualify as an expert. Id. at 1208. Instead, the court should

have recognized the witness as an experienced lay witness and permitted him to testify concerning

his ability to execute specific tasks. The witness’s conduct could help the jury understand the extent

to which monocularism does or does not impede the ability to function as an officer.

153. See, e.g., United States v. Denny, 48 F. App’x 732, 737–38 (10th Cir. 2002) (upholding the

admissibility of a witness’s statement that defendant was “extremely intoxicated” as appropriate lay

witness testimony); Asplundh Mfg. Div. v. Benton Harbor Eng’g, 57 F.3d 1190, 1196 (3d Cir. 1995)

(listing lay witness opinion that an individual appeared drunk as exemplary of Rule 701 testimony);

State v. Hall, 353 N.W.2d 37, 43 (S.D. 1984) (upholding lay testimony of police officers that

defendant was intoxicated based on the officers’ previous interactions with intoxicated individuals).

154. Of course, even in these situations, an opinion based solely on comparison with third parties

who exhibited similar behavior by definition does not take into account the personal situation of the

actor and will be wrong if the symptoms are caused by insulin imbalance or some other condition

that manifests itself in similar symptoms. The use of reliable methodology, such as a blood test or a

breathalyzer test, will avoid this problem.

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that the inferences drawn from the third party conduct are fair in the context

of the particular case. In addition, the court should guard against the

possibility that the opinion invites the jury to view the person in question as

sharing character traits with the third parties and acting in conformity with

that character.

Unfortunately, courts sometimes admit opinion based on third party

conduct without adequate scrutiny.

155

For example, courts routinely admit

law enforcement testimony concerning drug jargon, opining that the

defendant’s words were actually code or jargon for drug-related terms. The

opinion concerning the meaning of terms is based on having heard third

parties use them in a context that revealed their meaning to the witness, and

inferring therefore that the defendant is using the terms in the same way.

156

This jargon testimony is merely lay opinion based on the conduct of third

parties. While the testimony may sometimes be admissible, the court should

ensure that the opinion witness has heard the exact jargon used in

sufficiently similar circumstances an adequate number of times to

reasonably infer that the defendant’s meaning is the same as that of the third

parties’ meaning.

B. How Experience Informs Expert Opinion

Most expert opinion also rests to some degree on the experience of the

witness.

157

However, regardless of the extent to which an expert relies on

experience, the expert must demonstrate a reliable methodology.

158

If the witness offers expert opinion, employing a specialized

methodology to develop inferences based in part on a rich experience base,

the court must inform itself about the methodology, assuring itself that the

methodology is reliable and was reliably applied to an adequate basis of

155. See infra Section VI.D.

156. United States v. Diaz, No. CR 05-00167 WHA, 2006 WL 2699042, at *2 (N.D. Cal. Sept.

19, 2006) (describing manner in which law enforcement officer arrived at understanding of jargon).

In Diaz, although it treated the witness as an expert, the court recognized that jargon testimony rests

on “repetition and context” and properly held that the officer should not have been permitted to

testify to the meaning of a phrase he had never heard used before. Id. at *3–4.

157. See David L. Faigman, Expert Evidence in Flatland: The Geometry of a World Without

Scientific Culture, 34 S

ETON HALL L. REV. 255, 259–60 (2003) (discussing basis for expert

testimony and noting that the “essence of the expert’s testimony is that this case is like other

similarly situated cases in the world”); Imwinkelried, Taxonomy of Testimony,

supra note 34, at 204

(arguing that experts necessarily rely on “accumulated, vicarious experience” and not solely on

personal experience). But see David Crump, The Trouble with Daubert-Kumho: Reconsidering the

Supreme Court’s Philosophy of Science, 68 M

O. L. REV. 1, 15–16 (2003) (complaining that expertise

based on experience does not fit into the analytical framework of Daubert or amended Rule 702).

158. See F

ED. R. EVID. 702 advisory committee’s note (emphasizing reliability requirement).

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information relevant to the case.

159

The court should ask what the witness

has done with the experience.

The line dividing expert opinion and lay opinion from a witness with

unusual experience is sometimes very fine.

160

In United States v. Kayne, for

example, the jury needed help determining the value of the rare coins the

defendants had allegedly sold for inflated prices.

161

The prosecution called

eight coin dealers to testify concerning the value of the coins, and the First

Circuit saw no error, noting that “[o]pinions of value are a traditional subject

of expert testimony.”

162

The witnesses were experienced and explained their

methods of assessing value.

163

The court did not elaborate on the witnesses’

methodology, but consider the possibilities: If a coin dealer merely assessed

value based on personal experience buying and selling similar coins, the

witness’s opinion should be treated as lay opinion. If the witness’s opinion

reflected the use of more far-reaching research and application of method,

164

the witness should be evaluated as an expert.

V. T

HE RISK OF ADMITTING OPINION BASED ON EXPERIENCE ALONE

Whether or not a witness is an expert, a party may seek to gain an

advantage by pushing the limits of permitted opinion testimony. The risk

with all experience-based opinion is that the jury will defer to the witness’s

159. If the expert cannot demonstrate a reliable connection between the facts and the opinion, the

opinion should be excluded. See Moore v. Ashland Chem. Inc., 151 F.3d 269, 277–79 (5th Cir.

1998) (concluding that trial court properly excluded aspects of opinion that were not shown to be

reliably grounded in science); Mark P. Denbeaux & D. Michael Risinger, Kumho Tire and Expert

Reliability: How the Question You Ask Gives the Answer You Get, 34 S

ETON HALL L. REV. 15, 48–

60 (2003) (discussing evaluation of witness whose expertise is based in part on experience).

160. See, e.g., Walker v. Soo Line R.R. Co., 208 F.3d 581, 591 (7th

Cir. 2000) (concluding that

witness whose professional experience included responsibility for safety of power facilities from

lightning was qualified to give expert testimony concerning the safety of the tower in which plaintiff

claimed to have been struck by lightning). The court did not elaborate on the witness’s experience.

Whether he was fairly treated as an expert would depend on whether he analyzed the tower’s safety

with the help of some reliable methodology acquired through his experience or whether he simply

used everyday reasoning and analogized from events in his experience.

161. United States v. Kayne, 90 F.3d 7, 11 (1st Cir. 1996).

162. Id. at 11–12.

163. Id. at 12.

164. The witness could research the provenance of the coins and the price the coins would bring

in different geographic markets and at different times. See United States v. Numisgroup Int’l Corp.,

170 F. Supp. 2d 340, 346–47 (E.D.N.Y. 2001) (discussing the use of an expert witness with a history

of leadership and success in the numinstatic community to testify as to the grade and appraisal value

of fraudulent coins); see also 95 A

M. JUR. 3D Proof of Facts §§ 38–41, 44–57, at 271–80, 285–337

(2009) (providing history of coin appraisal and grading, including how a witness may be considered

an expert in the field, and the role of opinion testimony as to coin value).

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inferential process simply because the witness has superior information.

165

A witness with a long history of observing a particular type of behavior may

draw conclusions based on those observations. However, experience alone

does not assure reliability.

166

A rich experience base does not necessarily

sharpen the witness’s reasoning process, and may deepen the witness’s

bias.

167

In addition, the admission of experience-based opinion creates the

opportunity for overreaching when courts fail to subject the opinion to

appropriate scrutiny. If the court fails to determine that the witness’s

experience base fits the issue and that the witness’s reasoning from

experience is reliable, a party may exploit the opportunity, pushing beyond

the fair use of the opinion witness. The party may use the opinion witness to

vouch for inferences only loosely supported by the evidence or add the

expert’s imprimatur to inferences more properly left for counsel’s

argument.

168

The party may elicit testimony that goes beyond what can be

rationally inferred from the witness’s particular combination of experience

165. While recognizing that expert opinion may be based on experience alone, the Advisory

Committee cautions courts to approach such testimony with care. See F

ED. R. EVID. 702 advisory

committee’s note; see also Bernstein, Expert Witnesses, supra note 16, at 482–83 (discussing

experience-based expertise under Rule 702).

166. See Bernstein, Expert Witnesses, supra note 16, at 486 (recognizing that “connoisseur”

testimony may not be admissible under Rule 702 because its reliability cannot be shown); D.

Michael Risinger et al., The Daubert/Kumho Implications of Observer Effects in Forensic Science:

Hidden Problems of Expectation and Suggestion, 90 C

ALIF. L. REV. 1 (2002) (considering ways in

which inaccuracy affects forensic sciences).

167. See Donlin v. Philips Lighting N. Am. Corp., 564 F.3d 207, 215 (3d Cir. 2009); United

States v. Paiva, 892 F.2d 148, 157 (1st Cir. 1989). In Donlin, the Third Circuit stated: “When a lay

witness has particularized knowledge by virtue of her experience, she may testify—even if the

subject matter is specialized or technical—because the testimony is based upon the layperson’s

personal knowledge rather than on specialized knowledge within the scope of Rule 702.” Donlin,

564 F.3d at 215. In Paiva, the First Circuit held that a drug user who had tasted and observed the

appearance of the questioned substance could properly testify to a lay opinion that it was cocaine.

Paiva, 892 F.2d at 157. The court stated:

Although a drug user may not qualify as an expert, he or she may still be competent,

based on past experience and personal knowledge and observation, to express an opinion

as a lay witness that a particular substance perceived was cocaine or some other drug.

. . . The liberalization of Rule 701 has blurred any rigid distinctions that may have existed

between lay witnesses and expert witnesses. . . . No longer is lay opinion testimony

limited to areas within the common knowledge of ordinary persons. Rather, the

individual experience and knowledge of a lay witness may establish his or her

competence, without qualification as an expert, to express an opinion on a particular

subject outside the realm of common knowledge.

Id. (citations omitted); see also Gross & Mnookin, supra note 67, at 156–58 (discussing the risk of

bias in law enforcement testimony based on experience); Moreno, supra note 5, at

30 (discussing the

hazards of reasoning from experience, which include the risk that the witness will rely on intuition or

will reach conclusions that are “personal, idiosyncratic, and subjective”).

168. See United States v. Garcia, 413 F.3d 201, 214 (2d Cir. 2005) (condemning the use of

introductory overview by opinion witness and remarking that “[t]he law already provides an

adequate vehicle for the government to ‘help’ the jury gain an overview of anticipated evidence as

well as a preview of its theory of each defendant’s culpability: the opening statement”).

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and observation, introducing opinion testimony that should not properly be

admitted.

169

Courts should distinguish between applying ordinary reasoning to a

broad experience base and applying some reliable methodology informed by

a broad experience base.

170

If the witness brings no reliable methodology

beyond everyday reasoning from observed similar situations to the proffered

opinion, the witness should be evaluated as a lay witness, subject to the

corresponding limitations. The court should question whether the opinion is

rationally based on the witness’s perception—whether it rests on inferences

fairly drawn from the witness’s experience—and the jury should be invited

to scrutinize the opinion in the same way.

In some cases, courts defer too readily to claims that a witness can draw

certain inferences based on experience. The courts should recognize that

mere experience, uninformed by methodological analysis, can lead to false

inferences.

171

The very experience base that qualifies the witness may bias

the witness to view new situations through a distorted lens—swayed by an

anecdotal sense of what inferences can be drawn, but not by any reliable

method of approach.

172

169. See, e.g., United States v. Mejia, 545 F.3d 179, 188–91 (2d Cir. 2008) (correcting trial

court’s erroneous admission of “expert” testimony that drew together hearsay from unspecified

sources to summarize the activity of the gang whose members were on trial, and noting “it is a little

too convenient that the Government has found an individual who is expert on precisely those facts

that the Government must prove to secure a guilty verdict—even more so when that expert happens

to be one of the Government’s own investigators”); United States v. Lopez-Medina, 461 F.3d 724,

744–45 (6th Cir. 2006) (noting that the prosecution’s expert witness’s testimony “essentially

amounted to an expert opinion that the items he himself had found in [the defendant’s] home

demonstrated a conspiracy to distribute cocaine”); see also United States v. Frazier, 387 F.3d 1244,

1264–65 (11th Cir. 2004) (holding that trial court properly excluded witness’s testimony concerning

physical evidence that would be “expected” in case of rape).

170. Courts have recognized, for example, that witnesses with medical training and expertise

should not be permitted to present an opinion based on their anecdotal observations in their medical

practice. See David E. Bernstein, The Admissibility of Scientific Evidence After Daubert v. Merrell

Dow Pharmaceuticals, Inc., 15 C

ARDOZO L. REV. 2139, 2147–60 (1994) [hereinafter Bernstein,

Admissibility of Scientific Evidence] (discussing cases);

see also Bernstein, Expert Witnesses, supra

note 16, at 476–77 (giving examples of scientific opinions based on “educated guesses” rather than

reliable methodology and proven to be wrong).

171. See Capra, The Daubert Puzzle, supra note 16, at 720–23 (discussing the problems of

anecdotal information as a basis for reliable opinion). Professor Capra points out two problems with

anecdotal information: it may be too limited a sample to support the conclusion and it may be too

dissimilar to support the conclusion. But see Crump, supra note 157, at 26 (assuming that Freud’s

dream theories should be admissible and referring to the exclusion of fingerprint ID as

“nonsensical”). Professor Crump seems reluctant to entertain challenges to accepted “science” even

though it is not shown to rest on reliable foundation.

172. See United States v. Hermanek, 289 F.3d 1076, 1096 (9th Cir. 2002) (noting that

government expert on drug jargon “appears at times to have interpreted cryptic language as referring

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Experience-based opinion may be skewed by perception bias—the

tendency to ascribe greater significance to observed facts than is

warranted.

173

A witness who identifies with a particular point of view will

view the data through that prism, skewing the inferences drawn.

174

As a

result, an untrained witness who has observed certain patterns may

overgeneralize, drawing bad conclusions. The witness may leap to

unwarranted inferences, ascribing more significance to the knowledge base

than it supports.

175

Reasoning solely from experience, the witness may be

prone to biased conclusions. One role of reliable methodology is to

minimize the impact of bias.

176

Another source of unreliability when a witness reasons from experience

to opinion without the benefit of reliable methodology has been referred to

as “post hoc reasoning.”

177

Post hoc reasoning imputes significance to

to cocaine simply because he believed appellants to be cocaine traffickers” and condemning “[s]uch

circular, subjective reasoning”); see also Bernstein, Expert Witnesses, supra note 16, at 453–55

(arguing that modern rules for expert testimony are necessary due to adversarial bias on the part of

expert witnesses); Risinger et al., supra note 166, at 19–26 (discussing how bias impacts observation

and conclusions).

173. See K

EITH A. FINDLEY, CONVICTION OF THE INNOCENT: LESSONS FROM PSYCHOLOGICAL

RESEARCH (B. Cutler ed., 2010) (discussing the problem of “tunnel-vision,” which leads law

enforcement officers and prosecutors to focus on information that supports their conclusion of a

defendant’s guilt while ignoring information that goes against the established conclusion);

TRENGTHENING FORENSIC SCIENCE, supra note 6, at 122 (discussing the “willingness to ignore

base rate information in assessing the probative value of information” and noting, for example, that

the significance of finding carpet fibers that match those in the suspect’s home depends on the base

rate—the rate at which those fibers are found in other homes); Moreno, supra note 5, at

(addressing the threat of prejudice posed by a law enforcement officer who offers expert testimony

based solely on subjective on-the-job experiences); see also United States v. Murphy, 457 F. Supp.

2d 1228, 1231 (D. Kan. 2006) (acknowledging that a witness’s bias may cause the court to enforce

requirements for expert testimony more strictly).

174. The committee that undertook a study of forensic sciences for the Academies of Science saw

bias as a sufficiently large problem and they recommended research on “human observer bias and

sources of human error in forensic examinations.” S

TRENGTHENING FORENSIC SCIENCE, supra note

6, at 24, 122–24 (discussing the role of bias and recommending a study of the issue and steps to

reduce the impact of bias); see also Angela Fagerlin et al., Reducing the Influence of Anecdotal

Reasoning on People’s Health Care Decisions: Is a Picture Worth a Thousand Statistics?, 25 M

ED.

DECISION MAKING 398, 398–99 (2005) (explaining the tendency of anecdotal information to

influence medical decisions); Emily L.B. Lykins et al., Beliefs About Cancer Causation and

Prevention as a Function of Personal and Family History of Cancer: A National, Population-Based

Study, 17 P

SYCHO-ONCOLOGY 967, 972 (2008) (explaining how beliefs concerning cancer are

influenced by personal and family history of cancer). One may also hypothesize that experts will

intentionally manipulate the evidence if courts do not adequately check for reliability. See Laser,

supra note 19, at 1409.

175. Bias may lead one to become anchored to an early conclusion or to “see patterns that do not

actually exist.” S

TRENGTHENING FORENSIC SCIENCE, supra note 6, at 123–24.

176. Id. at 122 (discussing bias).

177. See Bernstein, Admissibility of Scientific Evidence, supra note 170, at 2147–49 (discussing

post hoc reasoning).

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observed events that is not statistically warranted.

178

Only the application of

reliable assessment can assure the court that the opinion witness is not

engaging in such faulty reasoning. Consider again the example of a law

enforcement witness who testifies that the defendant’s use of a rental car

indicates that defendant is an experienced narcotics trafficker.

179

The

agent’s opinion ascribes criminal significance to facially neutral conduct.

The agent did not bring any special methodology to the opinion interpreting

the defendant’s conduct; the agent brings only experience—repeated

observations of similar conduct—and pooled information gathered from

other law enforcement agents. Both the agent and the sources of the pooled

information are biased sources. The result may be a biased and unwarranted

opinion. Before allowing the opinion, the court should analyze it closely.

The testimony of this law enforcement witness should not be viewed as

expert opinion.

180

No methodology plays a role in arriving at the conclusion

that use of a rental car suggests an experienced drug dealer. In addition to

the witness’s own observations of this and of prior drug transactions, the

witness may have obtained information from other agents either anecdotally

or through some sort of training classes. In effect, these amount to a single

argument: that the witness is an expert by virtue of access to the law

enforcement community’s pooled information. But the collective

information is derived from pooling experience-based knowledge and

beliefs, without subjecting the information and conclusions to testing under

the lens of some reliable methodology. The reasoning underlying the expert

opinion, while collective, is familiar lay reasoning applied by a group that is

biased by its focus on investigation of narcotics trafficking: “We have seen

this happen often enough that we think it is significant in this particular

way.” The court should not allow that conclusion to be presented to the jury

without scrutinizing its foundation and justification. Before allowing this as

178. See id. (discussing illustration of a physician who observes a small sample of children who

develop a brain tumor after receiving measles vaccine and infers a causal relationship). Professor

Bernstein criticizes the courts for accepting such reasoning too readily, noting that family physicians

often gave such testimony. Id. at

2145.

179. United States v. Figueroa-Lopez, 125 F.3d 1241, 1243 (9th

Cir. 1997); see also Capra,

Distinguishing Between Lay Witnesses, supra note 3, at 3, 34 (discussing Figueroa-Lopez). In

Figueroa-Lopez, the Ninth Circuit rejected the prosecution’s argument that the opinion was

admissible as lay opinion, but held that the opinion would be admissible only if the witness was

qualified as an expert. Figueroa-Lopez, 125 F.3d at 1247.

180. See United States v. Moore, 521 F.3d 681 (7th Cir. 2008) (noting that to arrive at the

conclusion that only guilty people are present at a drug deal, the law enforcement expert “assumes

that everyone present is culpable and uses that assumption as the ‘proof’ of culpability,” and

condemning the reasoning as unreliable).

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expert opinion, the court must demand that some reliable methodology be

employed to counteract the effect of inferences drawn by biased observers.

The agent’s opinion should be evaluated as lay opinion. The court

should gather enough information about the agent’s experience base to

assess the relationship between the information known to the agent and the

proffered opinion, asking if the agent’s conclusion is rationally related to the

facts perceived. The court cannot properly evaluate the opinion without

information about the frequency of drug deals not involving rented cars, the

frequency and characteristics of drug deals involving rental cars, and the

frequency of use of rental cars for other purposes in the relevant community.

The court can assure that the witness’s opinion is fairly grounded in

observed facts and not skewed by the witness’s bias only if it is fully

informed on the underlying basis.

VI. S

CRUTINIZING EXPERIENCE-BASED OPINION:

PPLYING RULE 701 WITH BITE

Courts often fail to subject experience-based opinion to proper scrutiny

under either the standards for lay opinion or those for expert opinion. At

times, courts accept too readily claims that a witness’s unspecified

experience base supports the inferences expressed in a lay opinion. At other

times, courts inappropriately accept claims that a witness has developed

relevant expertise from experience alone. In both situations, juries are

permitted to hear unsupported opinion testimony that should be deemed

inadmissible.

The following subsections detail five steps the courts should take to

control the use of experience-based opinion testimony. These steps should

be added to the comments to Rule 701 to provide stronger protection from

unfounded and unreliable opinion testimony. First, instead of treating

witnesses as experts by virtue of their experience and training, the court

should evaluate them as experienced lay witnesses. Second, the court should

not take at face value claims of expertise based on training or shared

experience; such claims may reflect nothing more than a set of unreliable

beliefs shared by a particular group. Third, the court should scrutinize

opinions informed by the witness’s experience, asking if the witness’s

experience base includes enough similar observations to support the

witness’s opinion. Fourth, the court should limit the extent to which a

witness can base an opinion on the conduct of unrelated third parties.

Finally, the court should check the inferences drawn from experience and

prohibit over-claiming, preventing the witness from drawing broad,

inadequately supported opinions.

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A. Evaluate Experience-Based Opinion as Lay Opinion

The lay opinion rule provides the preferred framework for analyzing

experience-based opinion because every lay opinion represents the

application of ordinary reasoning to the witness’s cumulated experience to

inform personal observation.

181

Accordingly, the courts should scrutinize

these opinions to ensure that they are rationally derived from the witness’s

experience base using everyday reasoning. Thus, the opinions of the

witnesses described in the hypothetical cases at the beginning of this

Article—Mona Lisa Vito, the law enforcement witness with experience in

drug cases, and the witness whose opinion rests on experience with

motorcycles—should be evaluated as lay opinion. Only when the witness

brings a reliable methodology to bear on the experience should the witness’s

testimony be evaluated under the rules governing expert testimony.

Specifically, the rules governing lay opinion should constrain opinion

testimony from witnesses who base their opinions on a deep experience

base, but no reliable methodology, by ensuring that the opinion is rationally

related to the witness’s knowledge and experience.

In some cases, courts erroneously admit opinion evidence that should be

excluded because it fails to satisfy the requirements for either lay or expert

opinion.

182

In Satcher v. Honda Motor Co.,

183

for example, the plaintiff

181. This will allow the proponent to present the opinion testimony without complying with the

pretrial disclosure rules applicable to expert testimony. See discussion of pretrial disclosure rules

supra Section III.C.2. The opposing party’s protection will lie in the trial court’s careful assessment

of the opinions offered and the court’s discretion to permit the opposing party additional time to

prepare cross-examination or obtain a responsive witness.

182. See, e.g., Betterbox Commc’ns Ltd. v. BB Techs., Inc., 300 F.3d 325 (3d Cir. 2002). In

Betterbox, a trademark infringement case tried before the amendments to Rule 702 went into effect,

the Third Circuit affirmed the admission of expert testimony based on experience, but acknowledged

that there was no showing of reliable methodology. Id. at 328–29. While an expert could apply

reliable methodology to determine the likelihood of confusion, these experts did not, so their

testimony should not have been admitted as expert testimony. Id. at 329–30. Nor was it clear that

their testimony satisfied the requirements for lay opinion. Id.

The testimony of forensic experts also poses problems that should be addressed by more

exacting application of the rules governing lay and expert opinion. See S

TRENGTHENING FORENSIC

SCIENCE, supra note 6, at 127–82 (challenging the reliability of a number of forensic sciences);

Beecher-Monas, supra note 20, at 74 n.126 (demonstrating the lack of reliability of bite-mark

evidence that is routinely admitted); Bernstein, Expert Witnesses, supra note 16, at 459–61 (forensic

testimony); Simon A. Cole, Where the Rubber Meets the Road: Thinking About Expert Evidence as

Expert Testimony, 52 V

ILL. L. REV. 803, 819–22 (2007).

Arson testimony illustrates the way in which courts have accepted claims of experience-

based expertise and admitted unfounded expert opinion where evaluation of the experience as a basis

for lay opinion should have prompted the courts to exclude the evidence. See S

TRENGTHENING

FORENSIC SCIENCE, supra note 6, at 173 (discussing the unreliability of arson expertise); David

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claimed that the motorcycle he had been riding at the time of his injury was

not crashworthy, alleging that it should have had crash bars. At trial, the

efficacy of using crash bars was disputed.

184

To support his claim, the

plaintiff called a former police officer as an expert to give his opinion that

the crash bars used on police motorcycles were “effective in reducing

injuries.”

185

The witness had no formal training that would give him

expertise in motorcycle design.

186

His claim to expertise lay in his nine-year

service on the police motor squad and his investigation of hundreds of

motorcycle accidents.

187

The witness brought no methodology to bear on his

assessment, but merely drew inferences based on his experience.

188

Thus,

his opinion was based on his application of everyday reasoning to draw

inferences from the many similar happenings he had observed. The trial

court allowed this witness to testify as an expert that, based on his

observations, he had the impression that crash bars provided effective

protection of the rider’s leg.

189

The court should have instead scrutinized

and excluded the testimony as lay opinion.

190

Low-level experience-based experts, such as law enforcement officers

with some experience in drug enforcement, who have been treated as experts

in the past, are unlikely to satisfy the reliability requirement now imposed on

expert testimony.

191

While they possess an unusual knowledge base as a

result of their experience, they apply no methodology beyond everyday

reasoning to draw inferences from their experience, and their opinions

Grann, Trial By Fire: Did Texas Execute an Innocent Man?, NEW YORKER, Sept. 7, 2009, at 42

(discussing the unreliability of arson evidence).

183. 52 F.3d 1311, 1313 (5th

Cir. 1995).

184. Id. at 1316. One manufacturer, Harley-Davidson, recommended against the use of crash

bars on police motorcycles. Id. at 1316–17. Engineering experts had conducted tests to determine

whether crash bars increased safety, with mixed results. Id. Some engineering tests suggested that

the utility of the crash bars depended on the precise nature of the motorcycle accident. Id.

185. Id. at 1316. The court held that permitting the witness to testify as an expert was not error.

Id. at 1317–18. The court provided the following account of his testimony:

Kenneth Harms, a former Miami police chief with experience on the motorcycle patrol

and in investigating motorcycles accidents, believes that police crash guards, particularly

those used on Harley-Davidson motorcycles, are effective in reducing injuries. Harms

conceded that he had no scientific or engineering expertise in motorcycle design. Harley-

Davidson has expressly recommended against the use of crash bars on its police

motorcycles.

Id. at 1316.

186. Id.

187. Id. at 1317–18. It was not clear that he had any experience with Honda motorcycles. See id.

188. Id.

189. Id.

190. The experts who testified disagreed about the use of crash bars and testified that the utility of

crash bars depended on the precise type of motorcycle crash. Id. at 1317. As a result, it seems

unlikely that the court would have permitted a lay witness, however experienced, to offer an opinion

on the safety of the motorcycle design. See id.

191. See F

ED. R. EVID. 702.

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should therefore be evaluated as lay opinion. This approach will preclude

reliance on information that has not been admitted in formulating their

opinions; to the extent the witness has relied on information that has not

been admitted, the witness must satisfy the reliability requirements applied

to expert opinion.

192

Their depth of experience may qualify such witnesses

to help educate the jury, but their lack of methodology should foreclose them

from expressing expert opinions.

Courts have often allowed law enforcement witnesses to testify as

experts, expressing their opinions concerning the significance of the

defendant’s conduct or use of language.

193

These witnesses rely on their

192. See United States v. Garcia, 413 F.3d 201, 216 (2d Cir. 2005) (noting that the agent-

witness’s testimony “depended, in whole or in part, on his specialized training and experience” and

therefore must be evaluated as expert testimony); Martinez & Arlyn-Pessin, supra note 3, at 28

(suggesting that the amendment to Rule 701 will modify the practice of allowing a lay witness to call

on special knowledge in forming opinions). This Article addresses only the issues that arise when

the witness is asked to give an opinion. If the witness simply shares her experience or specialized

knowledge with the jury, the problem may not arise. For example, in United States v. Caballero, the

defendants argued that certain prosecution witnesses should have been treated as experts even

though they had not expressed opinions. United States v. Caballero, 277 F.3d 1235, 1246 (10th

Cir.

2002). The defendants suggested that the witnesses were experts merely because they “presented

specialized knowledge, and because their testimony was based on their perceptions, education,

training and experience.” Id. The witnesses testified concerning INS procedures and also

summarized the defendants’ bank accounts and files. Id. The court distinguished between opinion

and other testimony and rejected the defendants’ argument, because the witnesses “expressed neither

a lay nor an expert opinion, as distinguished from a statement of fact as to what they had witnessed

during their respective careers.” Id. at 1247; see also United States v. Hamaker, 455 F.3d 1316 (11th

Cir. 2006) (allowing FBI financial analyst to testify as a lay witness to review and summarize

voluminous records from the defendant’s company). In Hamaker, the Eleventh Circuit did not view

the witness’s testimony as calling on any expertise. The court stated:

To prepare for his testimony, Odom simply added and subtracted numbers from a long

catalogue of MCC records, and then compared those numbers in a straightforward

fashion. As Odom himself explained at trial, while his expertise and the use of computer

software may have made him more efficient at reviewing MCC’s records, his review

itself was within the capacity of any reasonable lay person.

Hamaker, 455 F.3d at 1331–32. The mere fact that the witness summarized records did not convert

him into an expert. Id.

193. See United States v. Decoud, 456 F.3d 996, 1012–13 (9th Cir. 2006) (holding that agent was

properly allowed to testify to drug jargon); United States v. Dukagjini, 326 F.3d 45, 52 (2d Cir.

2003) (discussing admissibility of expert testimony on drug operations and drug jargon); United

States v. Watson, 260 F.3d 301, 307 (3d Cir. 2001) (summarizing the range of subjects on which

prosecution experts have been permitted to testify in narcotics cases); People v. Barnes, 19 Cal. Rptr.

3d 229, 237–40 (Ct. App. 2004) (discussing admissibility of drug profile evidence). In Watson, the

Third Circuit stated:

The courts that have considered this issue have recognized the operations of narcotics

dealers as a proper field of expertise. It is well-established that government agents may

testify to the meaning of coded drug language under Fed. R. Evid. 702. United States v.

Gibbs, 190 F.3d 188 (3d Cir. 1999); see also United States v. Theodoropoulos, 866 F.2d

587, 590–91 (3d Cir. 1989), overruled on other grounds, United States v. Price, 76 F.3d

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experience and training to support their opinion testimony.

194

They do not

employ any reliable methodology.

195

Instead, law enforcement witnesses

526 (3d Cir. 1996); United States v. Plunk, 153 F.3d 1011, 1017 (9th Cir. 1998) (noting

that the jargon of the narcotics trade and drug dealers’ code language are proper subjects

of expert opinion), cert. denied, 526 U.S. 1060, 119 S. Ct. 1376, 143 L. Ed. 2d 535

(1999); United States v. Delpit, 94 F.3d 1134, 1145 (8th Cir. 1996) (same); United States

v. Boissoneault, 926 F.2d 230, 232 (2d Cir. 1991) (same). In addition, “experienced

narcotics agent[s] may testify about the significance of certain conduct or methods of

operation to the drug distribution business, as such testimony is often helpful in assisting

the trier of fact understand the evidence.” United States v. Griffith, 118 F.3d 318, 321

(5th Cir. 1997) (quoting United States v. Washington, 44 F.3d 1271, 1283 (5th Cir. 1995),

cert. denied, 514 U.S. 1132, 115 S. Ct. 2011, 131 L. Ed. 2d 1010 (1995)). Thus, the

operations of narcotics dealers have repeatedly been found to be a suitable topic for

expert testimony because they are not within the common knowledge of the average

juror. Theodoropoulos, 866 F.2d at 590–92. Therefore, we reject Watson’s argument;

knowledge of the operations of narcotics dealers is a proper field of expertise.

Watson, 260 F.3d at 307.

194. See, e.g., United States v. Lopez, 547 F.3d 364, 373 (2d Cir. 2008) (law enforcement witness

permitted to testify as expert because of his lengthy experience); United States v. Throckmorton, 269

F. App’x 233, 236 (3d Cir. 2008) (concluding that officer testified as an expert because he “brought

the wealth of his experience as a narcotics officer to bear” and holding that agent’s opinion should

not have been admitted in the absence of proper pretrial notice).

195. See Amstutz & Harges, supra note 20, at 74–75 (discussing credentials of law enforcement

experts); Moreno, supra note 5, at

21–22, 33–35 (discussing lack of reliable methodology underlying

drug jargon expert testimony). Amstutz and Harges suggest the following questions as the gauge of

reliable law enforcement methodology:

[ ] To your knowledge does your department or agency subscribe to what the education in the

field of narcotics in law enforcement suggests?

[ ] Does your agency often conduct investigations with other local, state or federal agencies?

[ ] Does your agency and/or the officers involved exchange current information regarding

narcotics-related information?

[ ] As a result does your department or agency keep current with changes in the field regarding

narcotics-related information?

[ ] Does your department use the suggestions and/or information from other agencies to update

its own practices in narcotics-related matters?

[ ] Would that information entail changes in the law?

[ ] Would that information entail changes in the way you conduct investigations?

[ ] As a result of the changes in procedures and/or tactics of narcotics traffickers does your

department also change in response to current narcotics activities?

[ ] Does your department and/or agency engage in activities and or investigations from which

to derive input or criticism for future operations?

[ ] Is there a school or academic facility that teaches such tactics or changes in tactics?

[ ] What agencies are identified as the leaders in teaching narcotics-related tactics and

techniques?

[ ] Have you or your department received specialized training by those agencies?

[ ] Do you often exchange information with the staff or agents of those agencies either in a

classroom setting or field setting?

[ ] Is that in an effort to develop a peer review of the practices currently in place?

[ ] Has your methodology been subjected to peer review?

[ ] Are the practices you use currently used by other experts in the area?

[ ] Has your technique or methodology been generally accepted in the relevant community?

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apply familiar reasoning to their experience base, and any expression of

opinion should be scrutinized under Rule 701 as lay opinion.

196

For example, in United States v. Garcia,

197

the Second Circuit

concluded that the witness called on “specialized knowledge” when he

testified to his opinion that the defendant was a partner in a drug

transaction.

198

The court supported its conclusion by stating that the

[ ] Has your technique or methodology been derived naturally and directly out of research you

conducted independent of this litigation, or have you developed your opinions expressly for

purposes of testifying?

[ ] Have you adequately accounted for obvious alternative explanations than yours?

[ ] Is your field of expertise known to reach reliable results for the type of opinion given?

Amstutz & Harges, supra note 20, at 96–97. The suggested questions test the witness’s experience

and access to pooled information, but do not target any reliable methodology.

196. See United States v. Glenn, 312 F.3d 58, 67 (2d Cir. 2002). In Glenn, the trial court allowed

a prosecution witness who had observed the defendant from some distance to testify that the bulge in

defendant’s pants shortly before the defendant allegedly shot the victim was a gun. Id. at 66. The

Second Circuit held that the testimony was not proper. Id. The witness lacked the personal

observation required for lay opinion, but was also not qualified to provide expert opinion. Id. at 67.

The court noted that the witness “did not arrive at his conclusions through reliable principles or

methods but through casual, sporadic observations of drug dealers over some unspecified time

period.” Id. Drug identification testimony also poses a particular problem. In some cases, lay

witnesses have been permitted to draw on their experience with drugs to identify a questioned

substance. See, e.g., United States v. Durham, 464 F.3d 976, 982–83 (9th Cir. 2006) (holding that

lay witness was properly allowed to give opinion that substance was marijuana given her experience

with marijuana and her multi-sensory opportunity to observe the questioned substance); United

States v. Paiva, 892 F.2d 148, 157 (1st Cir. 1989) (permitting lay witness to express opinion that

substance was cocaine based on her personal experience with drugs). Courts should proceed

cautiously in this area. In the absence of chemical analysis, no witness should be permitted to testify

to a substance’s identification; instead, a witness should be restricted to the opinion that a substance

“appeared to be” a particular substance. An experienced lay witness cannot rationally arrive at a

more definite opinion using everyday reasoning due to the fact that other substances may mimic

illegal drugs. Furthermore, training in drug related law enforcement does not qualify a law

enforcement officer as an expert in drug identification. Only scientific methodology can reliably and

definitely identify a questioned substance as a particular drug.

197. 413 F.3d 201.

198. Id. at 216–17. In Garcia, the court summarized the basis of the witness’s testimony and

concluded he had testified as an expert:

Klemick testified that his opinion as to the various conspirators’ roles was based on

“intercepted phone conversations and research of law enforcement databases and

surveillance.” Focusing simply on the wire intercepts, we observe that Klemick’s review

of these conversations was hardly that of an average person. To highlight this very fact

for the jury, the government specifically elicited that Klemick had reviewed thousands of

intercepted conversations in the course of various narcotics investigations, and that he

had had the benefit of cooperating witnesses’ insights on some of these occasions. Based

on this experience, certainly outside the ken of the average person, Klemick informed the

jury that he did not expect to overhear explicit references to drugs on the intercepted

tapes; his experience taught him that drug dealers generally used code words when

referring to their illicit transactions. . . . Further, based on his “training and experience,”

Klemick knew that when targets discussed kilogram quantities of drugs, that meant they

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witness’s reasoning process was that of a narcotics officer, not an average

person.

199

To the contrary, while the witness had a broader experiential

background than most lay people, he employed the basic analytical approach

of making inferences from that experience base and the observed facts.

200

Such testimony should be evaluated as lay opinion.

In some instances, assessing the testimony as lay rather than expert

opinion would lead to its admissibility.

201

For example, in United States v.

were likely acquiring drugs for distribution rather than personal use. When he overheard

references to dollar amounts, he could assess their significance in light of his specialized

knowledge that the price for a kilogram of cocaine in the New York market at the

relevant time was $20,000 to $30,000. . . . Training and experience had further taught

him that quality could affect where within this range cocaine was priced, as could the

number of middlemen in the distribution chain between the foreign supplier and the New

York purchaser.

In sum, when Klemick concluded from wiretaps, database information, and surveillance

observations, that Garcia was a “partner” with Valentin in receiving cocaine from

DeArmas, and that his responsibilities included testing the quality of the cocaine, his

reasoning process was not that of an average person in everyday life; rather, it was that of

a law enforcement officer with considerable specialized training and experience in

narcotics trafficking.

Id. (citations and footnotes omitted); see also Watson, 260 F.3d at 307–08 (permitting three

agents to testify as experts on the basis of their experience).

199. Garcia, 413 F.3d at 217.

200. Id.

201. See, e.g., United States v. Spotted Elk, 548 F.3d 641, 662–63 (8th Cir. 2008) (experienced

drug enforcement agent testified that cash was wrapped in Saran wrap to mask the odor to prevent

detection by police dogs, that packages of cocaine were coated in grease to mask the smell, and that

pieces of tinfoil had been used to smoke cocaine); United States v. Vesey, 338 F.3d 913, 916–18

(8th Cir. 2003) (discussing admissibility of testimony from defense witness who was an experienced

drug dealer and confidential informant). In Spotted Elk and Vesey, the witness’s experience would

have provided the basis for lay opinion, and his testimony should not have been assessed as expert

testimony. See Spotted Elk, 548 F.3d 641; Vesey, 338 F.3d 913; see also United States v. Lee, 339

F. App’x 153 (3d Cir. 2009). In Lee, a government agent was permitted to testify as an expert on the

basis of “specialized knowledge of drug distribution networks and narcotics trafficking.” Lee, 339

F. App’x at 158. The court summarized the witness’s testimony as follows:

Agent Parks testified on aspects of drug trafficking in the Philadelphia area, none of

which are common knowledge among lay persons serving as jurors. Among other points,

Agent Parks testified regarding the manner in which heroin is typically packaged,

bundled, stamped and sealed in the Philadelphia area, how many individual packets are in

a bundle, and how those packets and bundles of packets are usually priced. Specifically,

Agent Parks testified that heroin typically costs between $70 and $90 dollars per gram,

and that, based on his conversations with the DEA lab, the amount of heroin in a bag

generally varies from .03–.05 grams, resulting in an average of .04 grams. Agent Parks

further testified that resellers typically purchased heroin in bundled format, as opposed to

individual packets. In addition, Agent Parks testified to some of the common names for

heroin in the Philadelphia area, including “dope” and “H.” Agent Parks also testified

concerning the relationship between resellers and suppliers, explaining that money may

be paid to the supplier up-front, at first, but that the reseller may be “fronted” the heroin

once trust is established between the two.

Id.

at 159. The defendant complained that the witness’s “expertise was merely to repeat information

that unidentified others communicated to him.” Id. at 158. The defendant further pointed out that

the witness had no methodology or claim to expertise based on personal extensive experience. Id.

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Oriedo,

202

the trial court allowed the agent to testify based on his own

observations that cocaine is packaged by cutting the end off a baggie and

then twisting or tying the drug into the removed corner of the bag.

203

appeal, the Seventh Circuit held that the testimony should have been

evaluated as expert opinion and should have been excluded because the

prosecution had failed to disclose it before trial.

204

Instead, the court of

appeals should have affirmed the admission of the evidence as permissible

lay opinion. The agent based his testimony on his personal observations and

experience, invoked no special methodology, and testified to an opinion that

was fairly derived using everyday reasoning.

205

Even the scholarly discussion does not get this issue right. Academics,

as well as courts, cite the three examples discussed below—the perfume

smeller, the beekeeper, and the farmer—as examples of experience-based

expert opinion. Categorizing these witnesses as experts ascribes too much

value to the witnesses’ experience and illustrates inappropriate deference to

claims based on experience in the absence of methodology. In most

instances, these witnesses provide opinion derived through everyday

reasoning by bringing their experience base to bear on observed facts.

206

The court held that the witness was properly qualified by specialized experience. Id. at 159. The

court described the witness’s training and experience as follows:

Parks, an FBI agent for over eleven years, testified that he received training in narcotics

and drug distribution organizations, participated in over 100 narcotics investigations, over

100 related searches, and wiretaps covering thousands of conversations concerning drug

activity, and that he debriefed numerous drug dealers and individuals involved with drug

distribution. In addition, Agent Parks testified that he consulted manuals and guidelines

issued by the Drug Enforcement Administration (“DEA”) and the FBI to stay current.

The District Court did not abuse its discretion in ruling that through such practical

experience and training, Agent Parks gained specialized knowledge in the field of drug

distribution networks and narcotics trafficking. That this was Agent Parks’s first time

testifying as an expert does not undermine those qualifications.

Id. The court did not address the reliability requirement of Rule 702 and did not explain how the

witness satisfied that requirement. A better approach would have been to assess the opinion under

Rule 701. The witness’s testimony could be admitted as lay opinion given the witness’s experience.

202. 498 F.3d 593 (7th

Cir. 2007).

203. Id. at 602–03.

204. Id. at 604.

205. See also United States v. Lopez, 547 F.3d 364, 373 (2d Cir. 2008) (discussing a law

enforcement witness whose opinions were based on what he had seen and not what he had been

told). In Lopez, the court should have concluded that the investigator’s opinion was admissible lay

opinion, provided he could cite sufficient instances in which he observed similar paraphernalia being

used in drug distribution.

206. See also Dale A. Nance, Reliability and the Admissibility of Experts, 34 S

ETON HALL L.

REV. 191, 233–36 (2003) (discussing example of “gestalt expert” who testifies to the value of

property based only on a combination of experience and a visit to the property). Like the other

examples, this gestalt expert is better viewed as an experienced lay witness who assesses value based

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604

Their testimony should be evaluated as lay opinion, scrutinized accordingly,

and excluded unless the court determines that the witness’s experience

supports the opinion through the application of everyday reasoning.

The perfume smeller: Some have suggested that a witness who has deep

experience as a perfume smeller should be permitted to provide an expert

opinion.

207

Instead, the witness is an example of a lay witness with unusual

experience. The witness does not draw on any broad field of research,

collective knowledge, or specialized method of analysis. To the contrary,

the claimed basis for the ability to form an opinion is the witness’s personal

experience of olfactory observation, a store of similar happenings. The court

should decide whether the witness’s particular experience base and the

witness’s sniffing of the scent in question permits the witness to form a

rationally based opinion as to the identity of the questioned scent.

208

The beekeeper: The beekeeper has also been cited as a witness whose

experience would support the expert opinion that bees always take off into

the wind.

209

The beekeeper’s claim to expertise is based on his extensive

on similar and dissimilar properties. The witness should be able to explain the points of similarity

and difference to demonstrate how the other properties’ prices lead to the opinion concerning the

value of the property in question.

207. See Kumho Tire Co. v. Carmichael, 526 U.S. 137, 151 (1999) (referring to the perfume

sniffer expert); Bernstein, Expert Witnesses, supra note 16, at 484–85 (discussing perfume sniffer

example); Crump, supra note 157, at 15. Crump also cites a garage mechanic’s testimony

concerning the price of repairs. Crump, supra note 157, at 15.

208. Interestingly, there is reliable methodology that could substitute for the sniffer’s experience-

based identification of the smell. See Raffi Khatchadourian, Annals of Science: The Taste Makers,

EW YORKER, Nov. 23, 2009, at 85 (discussing experienced tasters and smellers and a scientific

means of assessing smells through the use of a Virtual Aroma Synthesizer, which chemically

analyzes scents). Another example of the use of smell to form an opinion can be found in cases in

which police officers testify that they recognized the scent of burning marijuana. To establish the

foundation for that opinion, the officer, sometimes visibly uncomfortable, must establish familiarity

with the scent. The officer may testify, for example, that the police periodically burn seized

marijuana so they will recognize the scent. This testimony establishes that the officer has a

sufficient experience base to express a lay opinion on the question, but does not demonstrate

expertise.

209. For example, in Berry v. City of Detroit, 25 F.3d 1342, 1349–50 (6th

Cir. 1994), the Sixth

Circuit explained:

The distinction between scientific and non-scientific expert testimony is a critical one.

By way of illustration, if one wanted to explain to a jury how a bumblebee is able to fly,

an aeronautical engineer might be a helpful witness. Since flight principles have some

universality, the expert could apply general principles to the case of the bumblebee.

Conceivably, even if he had never seen a bumblebee, he still would be qualified to testify,

as long as he was familiar with its component parts.

On the other hand, if one wanted to prove that bumblebees always take off into the

wind, a beekeeper with no scientific training at all would be an acceptable expert witness

if a proper foundation were laid for his conclusions. The foundation would not relate to

his formal training, but to his firsthand observations. In other words, the beekeeper does

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experience observing bees. Unless the beekeeper brings reliable

methodology to bear on the question of whether bees always take off into the

wind, the beekeeper’s opinion should be governed by the lay opinion rule.

The court should determine whether the beekeeper’s experience includes

enough observations of bees taking off in varying conditions to reasonably

draw the conclusion. The court should scrutinize the opinion, recognizing

that the testimony is based on anecdotal, impressionistic observation and

may also be influenced by beekeeper lore—the possibly inaccurate shared

belief that bees always take off into the wind.

An expert opinion concerning these flight patterns must be derived

through reliable methodology. To bring such methodology to bear on bee

behavior to determine whether bees always take off into the wind,

researchers could subject bees to systematic observation.

210

Bee takeoffs

into the wind and not into the wind could be counted and analyzed. If only

into-the-wind takeoffs were observed, statistical analysis could assess the

likelihood that the observations were the result of chance.

211

The resulting

data would support an expert opinion.

The farmer: The farmer who offers an opinion concerning the most

effective methods of shoring an irrigation ditch or the effectiveness of

specific fertilizers has also been advanced as an example of an experience-

based expert.

212

Like those discussed above, this witness should be treated

as a lay witness testifying based on unusual personal experience.

not know any more about flight principles than the jurors, but he has seen a lot more

bumblebees than they have.

See also United States v. Jones, 107 F.3d 1147, 1158 (6th

Cir. 1997) (citing beekeeper example and

quoting Berry to explain why handwriting witness should be permitted to give expert opinion);

Bernstein, Expert Witnesses, supra note 16, at 480 (discussing beekeeper as example of “connoisseur

testimony”).

210. Hives and bees in locations away from the hive could be filmed over a period of time and in

a variety of conditions.

211. See Moreno, supra note 5, at 33–35 (suggesting how methodology could be applied to drug

jargon testimony).

212. Professor Imwinkelried, asking whether a witness should be permitted to testify to an

opinion based on “a ‘few’ instances of supporting experience,” turns to the example of a farmer

offering testimony concerning fertilizer. Imwinkelried, The Next Step,

supra note 11, at 2290–91.

He concludes that a farmer, offering the expert opinion “that a particular chemical compound is one

of the effective fertilizers for a particular crop” in the county, should be permitted to testify even if

he has only a few confirming experiences. Id. at 2291. Imwinkelried bases his conclusion in part on

the limited nature of the opinion, noting that the witness “is not claiming that the fertilizer in

question is the only effective one or the one universally used.” Id.; see also Fed. Crop Ins. Corp. v.

Hester, 765 F.2d 723, 728 (8th Cir. 1985) (admitting testimony of neighboring farmers who had

experience growing corn on land similar to the defendant’s as expert testimony on the question of

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The farmer uses everyday reasoning and does not bring any reliable

methodology to bear. The farmer merely applies ordinary reasoning to draw

inferences from her experience base. As a lay witness, the farmer should not

be permitted to express the opinion unless her experience base—the number

of similar and dissimilar events the farmer has observed—is sufficient to

give rational support to the opinion. The court should assure itself that the

combination of observed facts and experience permits the witness to draw

the opinion using everyday reasoning. If the witness’s experience is too

limited, either because the farmer has observed too few relevant events or

because the farmer’s experience base is too skewed to similar or dissimilar

events, the court should exclude the opinion testimony.

B. Be Skeptical of Claimed Expertise Based on Shared Experience

Another risk when a witness offers experience-based opinion is that the

witness will draw on information pooled by those with related experience,

but not subjected to reliability testing. When a witness in a field without

methodology claims expertise based in part on “training,” the training may

consist merely of a formal process for sharing experiences and the inferences

drawn from those experiences.

213

This pooled information, not tested for

reliability, is inadmissible hearsay and could not be presented to the jury.

The court should not permit the pooled information to be admitted through

opinion testimony, either explicitly as the stated basis for the opinion or

implicitly by presenting the opinion without elucidating the basis.

The extrapolation of inferences by applying ordinary reasoning to

anecdotal information is not generally permitted.

214

Lay opinion must be

based on the witness’s own experience and knowledge, not on information

relayed from others. Furthermore, the mere sharing of information does not

transform the witness’s opinion from a lay opinion into an expert opinion.

For example, suppose a witness owns and drives a particular make and

yield). The testimony would better be analyzed as lay opinion, permitting the witnesses to testify on

the yield from defendant’s land if they had sufficient similar observations to support the opinion.

213. See United States v. Lee, 339 F. App’x 153, 158–60 (3d Cir. 2009) (upholding expert

testimony by a law enforcement agent, based largely on his access to pooled information and general

experience in the police force, and stating that in the absence of methodology, reliability focuses

mainly on personal knowledge or experience); United States v. Lopez, 547 F.3d 364, 373 (2d Cir.

2008) (upholding the expert testimony of a law enforcement officer without reliable methodology,

based on experience and information gained during his time as a detective investigating drug crimes,

including information learned from other agents, as well as his own personal experience); United

States v. Watson, 260 F.3d 301, 307 (3d Cir. 2001) (stating that Rule 702 qualifications have been

interpreted liberally, often allowing expert testimony by law enforcement officers based on training

and experience, rather than methodology); United States v. Poulsen, 543 F. Supp. 2d 809, 810–11

(S.D. Ohio 2008) (stating that experience-based expert testimony may satisfy the Daubert reliability

requirement, and upholding the testimony of an FBI agent based solely on his training and

experience, and not scientific methodology).

214. See discussion of similar happenings supra Section IV.A.1.

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model car and has felt the car pull to the left when she applies the brakes—

her personal experience base. Suppose that she has also spoken to others

with the same car and they have reported the same effect, and, further, that

she has looked at online sources that report this effect. That added

information does not qualify her to give an expert opinion on the braking

action.

215

Moreover, the additional information is inadmissible hearsay and

cannot inform the witness’s lay opinion. To admit a lay opinion based on

such pooled information would inject a possible source of unreliability that

neither the court nor the jury could adequately assess.

Allowing an experience-based witness who possesses no reliable

methodology to testify as an expert and rely on pooled information generates

an even greater risk of unreliability. In United States v. Lee,

216

the court

rejected the defendant’s argument that the agent should not have been

permitted to testify as an expert because he was simply relying on what other

agents had told him. The court concluded that the agent could rely on this

pooled information if it was the type of information reasonably relied upon

by experts in the field.

217

The problem is that any group with a shared

experience base will vouch for the practice of relying on pooled

information—the lore of the group.

218

When the court treats a witness as an

expert because the witness has access to this pooled information, the court

allows the witness to present the views of the group in the guise of expert

opinion. In this way, the witness transmits to the jury the beliefs of a group

of self-proclaimed and possibly biased experts who employ no reliable

method to draw inferences from their pooled information. Not only does

215. See United States v. Murphy, 457 F. Supp. 2d 1228, 1233 (D. Kan. 2006) (rejecting the

argument that defense witness’s conversations with many marijuana growers established expertise).

By contrast, shared information can play a key role in determining whether a law enforcement

officer had probable cause. See United States v. Garcia, 413 F.3d 201, 213 (2d Cir. 2005) (stating

that, while pooled information is permissible testimony in probable cause challenges, it is not

admissible at trial under Rule 701); see also Thacker v. City of Columbus, 328 F.3d 244, 256 (6th

Cir. 2003) (finding probable cause based on the information “gathered collectively” and shared by

the police officers at the scene); Dubner v. City of S.F., 266 F.3d 959, 966 (9th Cir. 2001) (noting

that probable cause may be established “through the collective knowledge of the officers at the

scene”); United States v. Cruz, 834 F.2d 47, 51 (2d Cir. 1987) (stating that “[t]he determination of

whether probable cause . . . exists can be based on the collective knowledge of all of the officers

involved . . . .”).

216. 339 F. App’x 153.

217. Id. at 157.

218. For example, it is quite likely that the beekeeper or the farmer, discussed supra Section

VI.A, has discussed the problem at hand (bees’ takeoffs or fertilizer) with other beekeepers or

farmers. A body of untested, but trusted, lore may have developed from this pooled information.

See Denbeaux & Risinger, supra note 159, at 15, 60 (discussing the problem of a “guild-like

group . . . who share the same beliefs and general methods”).

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such an approach fail to ensure reliability, it actually heightens the threat of

unreliability while clothing the witness in the mantle of specialized

knowledge and expertise.

This problem exists in some areas of forensic science. A forensic

witness’s expertise may rest on having been apprenticed by a more

experienced expert, neither of them having grounding in a methodological

approach.

219

Arson investigators, for example, have often been permitted to

testify as experts, even though their assessments rest on experience and

shared “wisdom” rather than developed and reliable methodology.

220

Based

219. STRENGTHENING FORENSIC SCIENCE, supra note 6, at 15 (discussing problems of

professional culture in the forensic sciences); see also Beecher-Monas, supra note 20, at 88–91

(demonstrating that even claims of methodology do not assure reliability and should be scrutinized);

Bernstein, Expert Witnesses, supra note 16, at 481 (discussing some forensic expert testimony as

examples of “connoisseur testimony”); Risinger et al., supra note 166, at 27–42 (discussing ways in

which results of forensic analysis are skewed by observer effects). Courts continue to accept claims

of expertise based primarily on experience and rely on the acceptance of an opinion by similarly

qualified experts to assure reliability. See, e.g., United States v. Santiago, 202 F. App’x 399, 401

(11th Cir. 2006) (holding testimony of arson expert qualified through experience was properly

admitted, noting in part that his “findings were subject to review by his co-workers and

supervisors”).

Handwriting analysis is also a field where analysis presented as expert analysis is not

supported by reliable methodology, but often seems to be the result of lore transmitted from one

“expert” to another. See United States v. Jones, 107 F.3d 1147, 1157 (6th Cir. 1997) (pre-Kumho

decision acknowledging that expert handwriting analysis is not supported by empirical evidence, but

nevertheless concluding it is admissible); D. Michael Risinger et al., Exorcism of Ignorance as a

Proxy For Rational Knowledge: The Lessons of Handwriting Identification “Expertise,” 137

U. PA.

L. REV. 731 (1989); see also United States v. Velasquez, 64 F.3d 844 (3d Cir. 1995) (discussing

handwriting expertise in case where expert summarized her analytical approach, but did not establish

its reliability; concluding that trial court should have admitted testimony of critic of handwriting

expertise). The National Research Council of the National Academies summarized its findings on

handwriting analysis as follows:

The scientific basis for handwriting comparisons needs to be strengthened. Recent

studies have increased our understanding of the individuality and consistency of

handwriting and computer studies and suggest that there may be a scientific basis for

handwriting comparison, at least in the absence of intentional obfuscation or forgery.

Although there has been only limited research to quantify the reliability and replicability

of the practices used by trained document examiners, the committee agrees that there may

be some value in handwriting analysis.

TRENGTHENING FORENSIC SCIENCE, supra note 6, at 166–67 (footnotes omitted). Some

handwriting witnesses also testify as experienced lay witnesses and are therefore subject to the

limitations of the lay opinion rule. See 1 B

ROUN ET AL., supra note 3, § 11, at 54 (cites recognition

of skilled lay observer on handwriting recognition).

220. D

AVID L. FAIGMAN ET AL., SCIENCE IN THE LAW: FORENSIC SCIENCE ISSUES § 7-1.1, at 339

(2002) (describing the process of using accepted tools and clues to determine the cause of a fire:

“Some of these clues are derived from sound science. Others are nothing more than a set of more or

less shared beliefs that may or may not be true. An opinion is then reached by these clues being

processed through each investigator’s personal experience, beliefs and assumptions—in addition to

or instead of any well tested model for analyzing fire evidence.” (footnotes omitted)). The

experience would include the observation of similar patterns at fires that the witness believed

resulted from arson and dissimilar patterns at fires that the witness did not believe resulted from

arson. Explorations of whether arson expertise rests on reliable methodology have now revealed the

speculative and unreliable nature of much expert testimony. See id. § 7-1.2, at 343 (reporting that

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on experience and pooled information, the witness would testify that certain

physical evidence (burn patterns or reactions of window glass) were signs of

arson, indicating that the fire was set and signaling where it originated.

221

The problems associated with pooled information infect arson testimony: An

arson “expert” would erroneously conclude that a fire resulted from arson

when it had not, and would then share the observations from the fire scene

with other arson investigators to support the belief that certain patterns

indicated arson—beliefs later shown to be wrong.

222

The courts that allowed

these arson investigators to testify as experts should have rejected claims of

expertise based on shared information, and instead evaluated and excluded

the offered testimony as lay opinion.

223

The use of pooled information that has not been tested by reliable

methodology is likely to compound the effect of inaccurate inferential

reasoning. When experience-based opinions and beliefs do not pass through

the crucible of a methodology that checks for accuracy and reliability, the

effect of perception bias or other distorting reasoning is reinforced. The

before Kumho was decided, “some insurance company attorneys began counseling fire investigators

to identify themselves as ‘experience-based’ experts, in an effort to avoid scrutiny under Daubert”);

TRENGTHENING FORENSIC SCIENCE, supra note 6, at 173 (discussing unreliability of arson

expertise); Grann, supra note 182, at 42 (discussing unreliability of arson evidence).

221. F

AIGMAN ET AL., supra note 220, § 7-1.1, at 341 (citing concrete spalling, crazed glass, and

burn pattern testimony as having been common and having been unsupported by empirical research).

Courts continue to accept claims of arson expertise based primarily on experience. See, e.g.,

Santiago, 202 F. App’x 399. In Santiago, the Eleventh Circuit concluded that an expert’s testimony

that the fire resulted from arson was properly admitted even though the witness was not a certified

arson investigator given his experience in the field. Id. at 401.

222. The National Academy of Sciences Report states:

Despite the paucity of research, some arson investigators continue to make

determinations about whether or not a particular fire was set. However, according to

testimony presented to the committee, many of the rules of thumb that are typically

assumed to indicate that an accelerant was used (e.g., “alligatoring” of wood, specific

char patterns) have been shown not to be true.

TRENGTHENING FORENSIC SCIENCE, supra note 6, at 173.

223. Had the courts evaluated the opinion as lay opinion, the courts should have excluded the

evidence, determining that the witness could not reach the offered opinions by applying lay

reasoning to the witness’s experience base. The witness could not know with certainty which of the

earlier observed fire sites resulted from arson and which did not. That missing knowledge injects a

risk that the witness would engage in questionable reasoning and arrive at unfounded conclusions. A

witness reasoning from experience uninformed by reliable methodology might conclude that,

because a particular fire pattern is present at the site of the questioned fire and was also present at the

site of an earlier fire, which the witness believed resulted from arson, the questioned fire must also

have resulted from arson. If the presence of the pattern also influenced the witness to conclude that

the first fire resulted from arson, the reasoning is circular and the basis for concluding the first fire

was arson is flawed. However, even if the witness knew with certainty that the earlier fire or fires

resulted from arson, lay reasoning does not support the conclusion that a particular burn pattern at

the earlier site suggests arson.

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entire lore may be skewed by faulty reasoning and by the resulting

expectations of those making the observations.

224

As a result, those relying

on the pooled information will become biased observers.

225

The courts

should recognize that a witness does not become an expert through the

transfer of unconfirmed lore and may be more likely than a witness without

that preconditioning to jump to unfounded conclusions.

C. Evaluate the Fit Between the Witness’s Experience and the Opinion

Once expertise is established, an expert witness is allowed to call on

undisclosed pools of information gleaned from others in the field, as well as

the expert’s own personal observations.

226

The expert is not required to

provide all the background information. A lay witness should not be

accorded similar latitude. Instead, the court must consider whether the

combination of the witness’s experience and observation of relevant facts in

the case allows the witness to derive the proffered opinion through the

application of everyday reasoning.

227

In some cases, the witness’s

experience base supports the lay opinion.

228

In others, however, the opinion

224. For example, a novice beekeeper will be told that bees take off only into the wind. That will

encourage the beekeeper to look for that phenomenon and discount anything the beekeeper observes

to the contrary.

225. In United States v. Abel, 469 U.S. 45 (1984), the Supreme Court explained bias as follows:

Bias is a term used in the “common law of evidence” to describe the relationship between

a party and a witness which might lead the witness to slant, unconsciously or otherwise,

his testimony in favor of or against a party. Bias may be induced by a witness’s like,

dislike, or fear of a party, or by the witness’s self-interest. Proof of bias is almost always

relevant because the jury, as finder of fact and weigher of credibility, has historically

been entitled to assess all evidence which might bear on the accuracy and truth of a

witness’s testimony.

Id. at 52.

226. See F

ED. R. EVID. 703.

227. See, e.g., United States v. Ayala-Pizarro, 407 F.3d 25, 28 (1st Cir. 2005) (holding that

officer’s testimony concerning certain aspects of narcotics trafficking was admissible lay opinion

where the officer laid out his experience in some detail; the testimony stayed within the realm of

inferences rationally based on the officer’s knowledge); United States v. Myers, 972 F.2d 1566,

1577 (11th Cir. 1992) (holding that officer was allowed to express lay opinion that burn marks on

victim’s back “were consistent with marks that would be left by a stun gun,” an opinion rationally

derived from his prior observations); see also F

AIGMAN ET AL., supra note 220, § 7-1.3.3, at 348

(suggesting that “[c]ourts would be well advised to unpack the claimed ‘experience’ in order to

discover what was learned from it and whether that something supports a valid and reliable expert

opinion”).

228. See, e.g., United States v. Oriedo, 498 F.3d 593, 602–04 (7th

Cir. 2007) (witness provided

opinion based on his own observations that cocaine is packaged by cutting the end off a baggie and

then twisting or tying the drug into the removed corner of the bag; the opinion should have been

allowed as admissible lay opinion).

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cannot be rationally derived by bringing the witness’s experience to bear on

the observed facts.

229

In Satcher v. Honda Motor Co.,

230

discussed above, the court allowed a

former police officer to testify to an expert opinion concerning the efficacy

of crash bars on police motorcycles.

231

The witness drew on his experience

serving on the police motor squad and his investigation of hundreds of

motorcycle accidents.

232

His opinion was based on his application of

everyday reasoning to draw inferences from the other motorcycle

accidents—other happenings—he had observed. The court should have

evaluated his testimony as lay opinion and should also have determined the

similarity or dissimilarity of the circumstances in those other accidents.

Without that inquiry, the court had no assurance that the opinion was

rationally based on the witness’s experience and the observed facts.

In United States v. Maher,

233

the court allowed the prosecution to

present lay opinion from a law enforcement officer that, based on his

training and experience, the Post-It note found in the defendant’s van was a

“drug note[],” or a “[d]rug distributor’s way of being organized.”

234

The

court should have been more exacting. First, the opinion was not supported

by any demonstration that the officer had sufficient experience with similar

uses of Post-It notes to support his opinion.

235

Without that information, the

229. See, e.g., id. In Oriedo, the Seventh Circuit approved the trial court’s decision to admit as

lay opinion the testimony of an agent who testified that he was “personally concerned about there

being two vehicles” because “more than one vehicle . . . raises concerns about” counter-surveillance.

Id. at 602. The Seventh Circuit concluded that the witness’s testimony involved only lay opinion

because the agent did not testify about counter-surveillance practices in the drug trade or

characterize what he saw as counter-surveillance. Id. In Oriedo, the opinion should not have been

admitted without a demonstration that the agent had an adequate basis in personal observation to

support the opinion. The court noted that the agent only testified to “his own state of mind while

observing this particular drug deal.” Id. Of course, the greatest problem with this testimony is that

the agent’s state of mind was entirely irrelevant in the jury trial, but the court did not address that

concern. This may represent an example of a court not differentiating between evidence relevant to

a Fourth Amendment question, but not relevant to the question of guilt or innocence. The agent’s

state of mind could contribute to probable cause, but was not relevant at the defendant’s trial.

230. 52 F.3d 1311 (5th

Cir. 1995).

231. Id. at 1316–18.

232. Id. at 1317–18.

233. 454 F.3d 13 (1st

Cir. 2006).

234. Id. at 24.

235. To be admitted as lay opinion, the officer’s opinion must be extrapolated from similar events

in his experience base, but the prosecution did not elicit testimony establishing that similar events

existed. The opinion testimony constituted a shortcut for evidence of similar events—instances in

which such notes had been found and had been shown to be drug records—and the connection of

those events to the defendant’s case through the officer’s opinion. If this aspect of the prosecution’s

case were unpacked, the trial court would have to go through a much more careful analysis. First,

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court could not ensure compliance with the requirement that the opinion be

rationally based on the witness’s perception.

236

Furthermore, the manner in

which it was presented gave the jurors no basis for independent assessment

and invited them merely to defer to the superior knowledge of the officer.

D. Limit Opinion Based on Third Party Conduct

The use of third party conduct to form the opinion that a defendant acted

in a way that was typical of particular criminal activity is a recurrent

problem in the testimony of law enforcement witnesses.

237

Experience-

based law enforcement opinion witnesses often testify to inferences based on

third party conduct. The prosecution uses these opinion witnesses to paint

the defendant with the criminality of others they have investigated. The

witness accomplishes this goal either by testifying that the defendant’s

apparently innocent conduct is actually criminal behavior because the

witness has seen other criminals behave in the same way or that the

defendant’s criminal behavior has particular significance not otherwise

apparent to the jury. In this manner, law enforcement witnesses have

labeled using Post-It notes,

238

riding a bicycle around the neighborhood,

239

and driving a rental car as conduct that signals involvement in drug

the prosecution would present evidence of the similar events—instances observed by this particular

officer (not recounted to him by others) and sufficiently similar to be probative; the court would

have to determine that these other instances cleared the hurdle of basic relevance under Rule 402 and

also had sufficient probative value to avoid exclusion under Rule 403 as being unfairly prejudicial.

Second, the court would have to determine that the officer’s opinion reflected a rational inference

from this pool of data and was helpful to the jury, even though the jury was now armed with as much

information as the officer. The claim that the officer participated in numerous drug cases should not

be allowed to substitute for more specific information about the officer’s particular basis of

knowledge concerning the use of drug notes.

236. See also United States v. Williams, 212 F.3d 1305 (D.C. Cir. 2000). In Williams, without

examining the basis for the officer’s opinion, the trial court permitted a patrol officer to testify as an

expert that drug users commonly carry guns for protection. Id. at 1306. When the court of appeals

examined the basis for the opinion, the court concluded that the witness had been involved in fewer

than twelve arrests involving firearm possession, not enough to support his opinion testimony. Id. at

1309. The court also concluded that the foundation was insufficient to support a lay opinion on the

issue. Id. at 1309–10. But see United States v. Gill, 513 F.3d 836, 847 (8th Cir. 2008) (dismissing

defendant’s argument that agent should not be permitted to testify about the connection between

firearms and drug trafficking because he had no experience with drugs and licensed firearms).

237. See generally Peter Schofield, Comment, Criteria for Admissibility of Expert Opinion

Testimony on Criminal Modus Operandi, 1978 U

TAH L. REV. 547 (discussing the use of testimony

concerning typical modus operandi to convince the jury that defendant’s conduct was criminal).

238. See, e.g., United States v. Maher, 454 F.3d 13, 17 (1st Cir. 2006); see also United States v.

Throckmorton, 269 F. App’x 233 (3d Cir. 2008) (discussing admissibility of officer’s testimony

about narcotics “owe-sheets”).

239. See United States v. Lopez-Medina, 461 F.3d 724, 744–45 (6th Cir. 2006) (allowing

prosecution’s fact witnesses to testify as expert witnesses and opine that the defendant was

conducting counter-surveillance when he left home on his bicycle, and that scraps of paper contained

notes related to drug transactions).

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dealing.

240

To invite the jury to connect weapon possession with drug-

dealing, officers have testified that drug dealers commonly carry guns for

protection.

241

The courts must ensure that these opinions do not reflect

unwarranted inferences of criminality drawn by biased witnesses.

The courts should also guard against the prejudicial impact of having a

witness attach criminal significance to the defendant’s otherwise innocent

conduct by characterizing it as a modus operandi typical of a particular type

of crime. Consider, for instance, the law enforcement expert’s testimony

that a defendant’s use of a rental car signaled that defendant was an

experienced narcotics trafficker.

242

The opinion rests on the inference that,

because some other drug traffickers act this way, the defendant’s action

marks him as a drug trafficker as well. The court should not give this

evidence a role in the defendant’s case. Generally, it is not permissible to

invite the jury to draw an inference about this defendant based on the

conduct of an unrelated third party. If the prosecution simply offered

evidence that a different defendant in a different case used a rented car, it

would be inadmissible because it lacks probative value and injects too much

risk of unfair prejudice.

243

If the court admits this lay opinion, the court

accepts the agent-witness’s conclusion that it has happened often enough to

be a drug trafficking practice. But neither the court nor the agent is in a

position to draw that inference. The agent’s opinion is suspect because the

agent’s sample of observation is skewed to include a disproportionate

number of drug transactions, leaving the agent unable to assess the use of

240. United States v. Figueroa-Lopez, 125 F.3d 1241, 1243–44 (9th

Cir. 1997); see also United

States v. Millbrook, 553 F.3d 1057, 1064–65 (7th Cir. 2009) (allowing agent to testify as an expert

that drug users pay in small bills, in order to explain defendant’s possession of $1000 in cash and

refute his claim that he was going to use it to pay an $800 utility bill), overruled on other grounds by

United States v. Corner, 598 F.3d 411 (7th Cir. 2010); United States v. Jeanetta, 533 F.3d 651 (8th

Cir. 2008) (allowing expert law enforcement witness to testify that Ziploc bags, radios, scanners,

cameras, monitors, night vision goggles and large quantities of cash were all associated with drug

dealing); United States v. Martinez-Avina, 234 F. App’x 688, 690 (9th Cir. 2007) (agent testified

that having air freshener and only one or two keys in a vehicle signaled that it was transporting

drugs).

241. See United States v. Farrish, 297 F. App’x 162, 165 (3d Cir. 2008) (listing the government’s

evidence that drug dealers commonly carry guns as support for defendant’s conviction); United

States v. Branch, 537 F.3d 582, 589 (6th Cir. 2008) (noting that “drug dealers frequently carry

weapons”); see also Williams, 212 F.3d at 1309–10 (holding patrol officer did not have enough

experience to testify to the opinion that drug users commonly carry guns for protection).

242. Figueroa-Lopez, 125 F.3d at 1243–44; see also Capra, Distinguishing Between Lay

Witnesses, supra note 3, at 3, 34 (discussing Figueroa-Lopez).

243. See supra Section IV.A.3.

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rental cars in the general population. Moreover, the agent is a biased

observer, watching for signs of narcotics trafficking.

244

The government’s use of the drug courier profile also illustrates the risk

of such testimony. When admitted as proof of guilt, the witness testifying to

the drug courier profile is allowed to list the aspects of the defendant’s

behavior that typify drug courier behavior.

245

The witness is permitted to

opine, and the jury is invited to infer, that the defendant is guilty because the

defendant shares these behaviors with others who have committed drug

offenses.

246

Courts have recognized that such testimony injects a substantial

risk of unfair prejudice and is generally improper.

247

The courts should

extend that cautious approach to other similar uses of third party conduct.

244. The opinion should also be excluded as expert opinion. Nothing assures the reliability of the

conclusion. The agent does not employ a reliable methodology to ensure that she does not ascribe

unwarranted significance to innocent behavior and act as a biased witness who may not reliably

decide the fair probative value of the instances of similar conduct in other criminal transactions.

Although the Advisory Committee acknowledged these types of law enforcement experts when Rule

702 was amended to reflect Daubert’s emphasis on reliability, the Committee did not explain how

the process employed by the agent differs from lay reasoning applied to a deep experience base and

satisfies the requirement of reliable methodology:

For example, when a law enforcement agent testifies regarding the use of code words in a

drug transaction, the principle used by the agent is that participants in such transactions

regularly use code words to conceal the nature of their activities. The method used by the

agent is the application of extensive experience to analyze the meaning of the

conversations. So long as the principles and methods are reliable and applied reliably to

the facts of the case, this type of testimony should be admitted.

ED. R. EVID. 702 advisory committee’s note.

245. See, e.g., United States v. Lui, 941 F.2d 844 (9th Cir. 1991). In Lui, the trial court permitted

an agent to testify that the defendant showed five characteristics of a drug courier:

(1) [A]lthough “heroin couriers have a hundred ways to smuggle heroin,” typically they

wrap it around their bodies or place it in false bottoms and tops of suitcases; (2) in

approximately 80 percent of smuggling cases, couriers use hard-sided suitcases; (3)

couriers often use the excuse of conducting business or visiting a relative in the United

States; (4) couriers create itineraries with multiple stops for short periods of time so as to

enter the United States from a “non-source” country to avoid detection; and (5) couriers

often use paging devices.

Id. at 846.

246. It has been noted that the profile can be adapted to fit almost any traveler. See, e.g., United

States v. Webb, 115 F.3d 711, 719 (9th Cir. 1997) (noting that the court has long been critical of

drug courier profiles); United States v. White, 890 F.2d 1012, 1014 (8th Cir. 1989); United States v.

Hernandez-Cuartas, 717 F.2d 552, 555 (11th Cir. 1983) (noting that “[d]rug courier profiles are

inherently prejudicial because of the potential they have for including innocent citizens as profiled

drug couriers”). The profile is more appropriately used as a test for reasonable suspicion to justify a

search or seizure than as an indicator of guilt at trial. See Ornelas v. United States, 517 U.S. 690

(1996) (drug courier profile information went towards forming reasonable suspicion); United States

v. Sokolow, 490 U.S. 1 (1989) (allowing drug courier information to form reasonable suspicion for

investigative stop); United States v. Lewis, 556 F.2d 385 (6th Cir. 1977). But see United States v.

Urrieta, 520 F.3d 569, 576 (6th Cir. 2008) (cautioning against using profile generalizations to

establish reasonable suspicion).

247. See United States v. Gutierrez-Farias, 294 F.3d 657, 662–63 (5th Cir. 2002) (holding that

admission of agent’s testimony concerning modus operandi of drug dealers was error); United States

v. Jones, 913 F.2d 174, 176–77 (4th Cir. 1990) (holding it was error to permit an agent to testify

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The courts should not defer to government claims that a witness,

whether expert or lay, is drawing fair inferences from the conduct of others.

Instead, the court should scrutinize the opinion. The court should not permit

the inference unless the party offering the opinion provides information

concerning base rates—how frequently or infrequently the same conduct

occurs in innocent contexts.

248

For example, the fact that packages of drugs

are frequently wrapped in duct tape may be helpful when trying to determine

the contents of a package wrapped in duct tape, but it does not support the

inference that possession of duct tape signals drug dealing. The base rate

undermines the inference: many who do not distribute drugs possess duct

tape. Without base rate information, the court should recognize the risk that

the opinion witness is presenting an unfounded inference, skewed by the

observer’s bias, and only rarely admit opinion testimony based on third party

conduct.

E. Prohibit Over-Claiming

The courts should prohibit experience-based witnesses from drawing

broad conclusions from the observed facts.

249

The cases illustrate efforts to

push opinion testimony past any reasonable limit.

250

“that crack dealers often sell crack in small quantities and keep the proceeds from the sales nearby

rather than in a bank” and “that crack dealers normally possess firearms and that crack users can be

distinguished from dealers by the amount of the drug that each keeps on hand”); United States v.

Quigley, 890 F.2d 1019, 1022 (8th Cir. 1989) (concluding profile evidence should not have been

admitted). The courts permit the use of drug courier profile testimony at trial to provide background

explaining why the defendant was stopped or arrested or to rebut certain defense claims. See United

States v. Sanchez-Hernandez, 507 F.3d 826 (5th Cir. 2007) (allowing agent’s testimony because it

was not precisely profile testimony and it served to rebut defendant’s claims of innocence); United

States v. Urbina, 431 F.3d 305, 311–12 (8th Cir. 2005) (allowing profile evidence to rebut

defendant’s claim that he was unaware of drugs in gas tank); United States v. Beltran-Rios, 878 F.2d

1208, 1212–13 (9th Cir. 1989) (allowing profile evidence to rebut defendant’s claim he was too poor

to be a courier).

248. S

TRENGTHENING FORENSIC SCIENCE, supra note 6, at 112.

249. See, e.g., United States v. Oriedo, 498 F.3d 593, 602 (7th

Cir. 2007) (approving admission of

agent’s testimony that he was “personally concerned about there being two vehicles” because “more

than one vehicle . . . raises concerns about . . . countersurveillance”); United States v. Grinage, 390

F.3d 746, 747–50 (2d Cir. 2004) (holding that trial court improperly permitted agent to provide

opinions based on his investigation and the content of 2000 recorded phone conversations describing

the criminal organization and the roles of various participants).

250. See, e.g., United States v. Meises, 645 F.3d 5 (1st Cir. 2011) (condemning use of an agent to

give broad overview of criminal case); Jinro Am. Inc. v. Secure Invs., Inc., 266 F.3d 993, 1001–06

(9th Cir. 2001) (holding that trial court properly excluded testimony about the tendency of Korean

businessmen to circumvent currency regulations and the ways in which they did so); Trevino v.

Rock Island Police Dept., 91 F. Supp. 2d 1204, 1206–08 (C.D. Ill. 2000) (reporting that plaintiff

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When agents are accepted as experts, they are sometimes permitted to

state quite broad opinions concerning the criminal character of a defendant’s

conduct.

251

In United States v. Brown,

252

for example, the courts allowed

law enforcement experts to opine that a particular apartment was used for

storing drugs, that the defendant’s stop at the house was “consistent with . . .

a drug delivery,” that the defendant had control over the apartment, and that

the defendant’s actions “were consistent with that of someone engaging in

counter-surveillance activities and attempting to destroy evidence.”

253

this way, the prosecution used its expert witnesses to endorse the inferences

the prosecution hoped to persuade the jury to draw.

254

These inferences

should be the subject of argument rather than testimony.

255

Even when a witness testifies to lay opinion, the party offering the

testimony may push the witness to over-claim. In United States v. Garcia,

for example, the prosecution presented the case agent at trial as a lay witness

to introduce the case by describing the roles played in the drug conspiracy

by the various defendants, and the trial court allowed the testimony.

256

This

wanted to use monocular police officer to testify to broad assertions about the performance of

monocular officers based only on his own experience).

251. See, e.g., United States v. Cruz, 363 F.3d 187, 197 (2d Cir. 2004) (concluding that

prosecution expert strayed from his expertise when he stated opinion concerning what defendant

meant by particular statement); United States v. Dukagjini, 326 F.3d 45, 59 (2d Cir. 2003)

(concluding that trial court had improperly permitted expert to provide opinion testimony outside the

scope of his expertise).

252. 110 F.3d 605 (8th Cir. 1997).

253. Id. at 610.

254. See also United States v. Lopez-Medina, 461 F.3d 724, 744–45 (6th Cir. 2006). In Lopez-

Medina, the prosecution’s fact witnesses also served as expert witnesses and stated opinions

concerning the criminal character of defendant’s conduct. Id. at 743. The Sixth Circuit concluded

that the trial court did not sufficiently inform the jury on the demarcation between the expert opinion

and the fact testimony, but did not condemn the opinion testimony. Id. at 745. The prosecution sees

such value in this testimony that it sometimes offers expert testimony on criminal behavior when it is

not relevant to the particular case. See, e.g., United States v. Vallejo, 237 F.3d 1008, 1015–16 (9th

Cir. 2001) (concluding that agent’s testimony on drug trafficking was not relevant to the case against

the defendant and noting that the government reported that it routinely introduces such testimony in

all drug cases).

255. See United States v. Moore, 521 F.3d 681, 683 (7th Cir. 2008) (prosecution expert testified

that no one who was not involved with the drug deal would be present at the deal); United States v.

Parra, 402 F.3d 752, 758–60 (7th Cir. 2005) (holding that agent properly testified to expert opinion

that defendant’s otherwise innocent behavior looking up and down the street constituted counter-

surveillance).

256. 413 F.3d 201, 208–09 (2d Cir. 2005) (recounting agent’s testimony). On appeal, the

government argued unsuccessfully that “a case agent may offer, at the beginning of a trial, a lay

opinion providing a summary overview of anticipated evidence.” Id. at 211. The Second Circuit

condemned this practice, but concluded it was harmless error and upheld the conviction. The court

stated: “Klemick’s opinion did more than provide a ‘summary’ of Garcia’s words and actions—by

whomever they were observed. It told the jury that Klemick, an experienced DEA agent, had

determined, based on the total investigation of the charged crimes, that Garcia was a culpable

member of the conspiracy.” Id. at 213. The court further noted:

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testimony should have been disallowed; the agent’s biased conclusions about

the defendants’ criminality went beyond helpful lay opinion and injected

substantial prejudice into the case.

When a witness states an experience-based opinion, even if the court

admits it as lay opinion, the proponent may present the witness and the

opinion in a way that suggests expertise. For example, when a law

enforcement witness provides a lay opinion, the prosecution may emphasize

that the opinion is based on experience and training, as well as participation

in other narcotics cases, thus clothing the opinion in the appearance of

expertise.

257

The trial court should prohibit such bolstering while the

witness is testifying, as well as during closing argument.

VII.

CONCLUSION

The classification of experience-based testimony as either lay or expert

is critical to its admissibility. However, the line demarking the categories is

difficult to determine, and courts do not always strike the proper balance.

Too often, witnesses with unusual or rich experience bases are permitted to

testify as experts despite employing no reliable methodology or analysis.

Absent such methodology, witnesses offering experience-based testimony

merely apply ordinary lay reasoning to their experience base. Such

everyday reasoning does not meet the reliability standard required of expert

testimony. Experience alone often fails to sharpen a witness’s reasoning

process and may sometimes deepen the witness’s bias. Thus, only witnesses

[T]his practice is particularly problematic in criminal cases because it allows “the

government to paint a picture of guilt before the [supporting] evidence has been

introduced.” We . . . condemn the practice of having a case agent offer a summary

opinion as to culpability before any evidence to support such a conclusion has been

presented for jury review.

Id. at 214; see Bigelow, supra note 3,

at 5–8 (discussing prosecution use of summary witnesses).

257. See, e.g., United States v. Oriedo, 498 F.3d 593, 602 (7th

Cir. 2007) (allowing as lay opinion

agent’s testimony, conveying a veiled claim of expertise, that based on his experience and training,

he could tell when there was counter-surveillance and that he observed counter-surveillance in the

defendant’s case); United States v. Maher, 454 F.3d 13, 24 (1st Cir. 2006) (opinion witness provided

no specific basis in past experience for reaching conclusion that Post-It notes were a “[d]rug

distributors’ way of being organized,” but alluded to his experience and training, thus suggesting that

the opinion rested on expert knowledge). In Maher, the agents’ search had yielded a large roll of

currency and approximately half a gram of heroin in the defendant’s pocket, and, in the van, a bag

which contained three sandwich bags of cocaine, a scale, and a Post-It note listing several names,

each with a number to the right. Maher, 454 F.3d at 17. Given this evidence, it is hard to

understand why the prosecution felt the need to elicit the officer’s opinion concerning the nature of

the Post-it note.

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who use reliable methodology to form their opinions should be permitted to

testify as experts.

Witnesses who derive their opinions by applying everyday reasoning to

their personal experiences should be treated as lay witnesses. Rule 701

provides the appropriate framework for scrutinizing experience-based

opinion testimony. The rule directs the court to ensure that the opinion is

rationally derived from facts perceived by the witness. The court should

assess the reasonableness of the witness’s inferences given the witness’s

experience and the facts known to the witness. Thus, the classification of

experience-based testimony as lay testimony will keep courts from

attributing inappropriate value and deference to such testimony.

Further, courts should apply Rule 701 with bite. Rather than accepting

at face value a witness’s claims based on training or shared experiences,

courts should recognize that groups sometimes subscribe to a set of shared,

but nonetheless unreliable, beliefs. Courts should also scrutinize whether

the witness’s experience base is sufficiently extensive to support the opinion,

limit the extent to which opinion testimony may be based on the conduct of

unrelated third parties, and insist that the witness refrain from over-claiming

by suggesting that a lay opinion rests on expertise or by drawing over-broad

inferences from the witness’s experience. By giving teeth to the lay opinion

rule, courts can avoid admitting opinion testimony that lacks a sufficient

basis and ensure that only reliable inferences fairly drawn from experience

are presented to the jury.