Chapter 9. Opinions, Experts, and Scientific Evidence 1

A. Lay Opinions 1

B. Expert Testimony 6

1. Permissible Subjects and Scope 6

2. Reliability 10

a. Court-Appointed Experts 11

*NB: This outline accords with Sklansky, Evidence: Cases, Commentary and Problems 4th ed.

Chapter 9. Opinions, Experts, and Scientific Evidence

A. Lay Opinions

Introduction

Lay witness: a witness who does not testify based on some special expertise.
Unlike older rules, lay witnesses are free to offer opinions even on ultimate issues.
To be admissible, opinions expressed by lay witness must be (1) based on witness’s own firsthand observations and (2) helpful to the jury.

FRE 701. Opinion Testimony by Lay Witnesses

If a witness is not testifying as an expert, testimony in the form of an opinion is limited to one that is:
- (a) rationally based on the witness's perception;
- (b) helpful to clearly understanding the witness's testimony or to determining a fact in issue; and
- (c) not based on scientific, technical, or other specialized knowledge within the scope of Rule 702.

FRE 704. Opinion on an Ultimate Issue

(a) In General—Not Automatically Objectionable. An opinion is not objectionable just because it embraces an ultimate issue.
(b) Exception. In a criminal case, an expert witness must not state an opinion about whether the defendant did or did not have a mental state or condition that constitutes an element of the crime charged or of a defense. Those matters are for the trier of fact alone.

Advisory Committee Note to FRE 701

Allows opinion and ultimate issue testimony, since witnesses often find difficulty expressing themselves in language which is not an opinion or conclusion. Differentiating between these and “facts” is practically impossible, and a necessity standard for admitting them didn’t work.
If attempts are made to introduce meaningless assertions which amount to little more than choosing up sides, exclusion for lack of helpfulness is called for by the rule.

Advisory Committee Note to FRE 704

Under FRE 701 and 702, opinions must be helpful to the trier of fact. FRE 403 provides for exclusion of evidence which wastes time.
- These provisions assure against admission of opinions which would merely tell the jury what result to reach.
- They also exclude opinions phrased in terms of inadequately explored legal criteria.
  - E.g.: “Did T have capacity to make a will?” would be excluded, whereas “Did T have sufficient mental capacity to understand the nature and extent of …” would be allowed.

United States v. Meling, 47 F.3d 1546 (9th Cir. 1995)

Facts:

D convicted of product tampering after he allegedly tried to poison his wife with bottles of Sudafed laced with cyanide, and covered his tracks by placing five other bottles of laced Sudafed on store shelves, resulting in the deaths of two people.
- After wife collapsed, D called 911 and feigned hysteria to 911 operator and paramedics.
D challenges TC admitting lay opinion testimony of the 911 operator and the paramedic, both of whom testified that D was feigning grief shortly after the poisonings.

Opinion (Kozinski):

FRE 701: Lay opinion testimony is admissible if it is rationally based on the perception of the witness and helpful to the jury in acquiring a clear understanding of the issue.
While treating wife, Paramedic had ample time to form the impression that D was feigning grief.
911 operator’s testimony was rationally based on her perception of D’s agitation during emergency call.
- Though a tape of the conversation was played in full, the jury was not in the same position as the 911 operator to compare D’s behavior with that of other emergency callers or to assess whether it was abnormal.
United States v. LaPierre: witness who has no previous exposure to defendant is no better situated than jury to identify the defendant from a surveillance photograph.
United States v. Jackson: eyewitness identification testimony is helpful to jury even if surveillance photographs are available, since eyewitness had opportunity to compare person in bank surveillance photograph with everyone she had ever met, whereas jury could only compare person in surveillance photographs to the defendant.
Affirmed.

Government of the Virgin Islands v. Knight, 989 F.2d 619 (3d Cir. 1993)

Facts:

D found guilty of voluntary manslaughter after he repeatedly struck V’s head with a pistol, and the gun discharged and killed V.
D challenges TC’s exclusion of an eyewitness’ and investigating officer’s testimony that firing the gun was an accident.

Opinion (Cowen):

FRE 701’s requirement that a lay opinion be rationally based on the witness’ perception requires the witness have firsthand knowledge of the factual predicates that form the basis for the opinion.
- TC properly excluded police officer’s opinion because he did not observe the assault.
- The eyewitness, by contrast, did have first-hand knowledge of the facts from which his opinion has formed.
Having met firsthand knowledge requirement of FRE 701(a), eyewitness’ testimony was admissible if it would help the jury resolve a disputed fact.
- If circumstances can be presented with greater clarity by stating an opinion, then that opinion is helpful to the trier of fact.
- Here, eyewitness’ testimony that D fired gun accidently would be helpful to jury.
  - Eyewitness described the circumstances that led to his opinion. However, it is difficult to articulate all the factors that lead one to conclude it was an accident.
To find an error harmless, court must be able to say it is highly probable the error did not contribute to the jury’s judgment of conviction.
- The jury could infer from circumstances in this case that the shooting was accidental.
  - Eyewitness was permitted to describe fully the circumstances that led to his opinion.
  - D himself testified it was an accident, and D counsel argued this theory.
- Eyewitness testimony may have been seen by jury as more credible than defendant’s...

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