Chapter 10

• Jurisdiction: New York

CHAPTER TEN

EXPERT WITNESS TESTIMONY

5

EXPERT WITNESS TESTIMONY§ 10.0

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[10.0] I. OVERVIEW

In general, the rule in New York is that if scientific, technical or other

specialized knowledge will assist the jury to understand the evidence or to

resolve factual issues, a witness qualified by knowledge, experience and

training as an expert may give his or her opinion about the issues in dis-

pute provided that testimony is based upon reliable facts or data.

Expert witnesses may express their opinions on relevant issues that are

beyond the knowledge of most people. Generally, the foundation must

include more extensive questions about the experts’ professional training,

experience, background and the data on which their opinions are based to

establish that they are experts in the field about which opinions will be

given.

There are three important reasons why expert witness testimony is

appropriate: is the issue to be litigated sufficiently removed from the

jury’s common experience and knowledge so that they need an expert’s

assistance to understand the trial issues; is the subject matter of the litiga-

tion amenable to expertise testimony; and does the proposed expert have

the necessary qualifications for his or her testimony and opinions.

New York requires experts to rely on procedures, techniques or meth-

odologies “generally accepted” as reliable by the relevant scientific com-

munity—the standard articulated in Frye v. United States1 and consistently

applied by New York courts to determine the admissibility of scientific

evidenc e.

The admissibility of expert testimony rests in the discretion of the trial

judge. Once the Frye “general acceptance” inquiry has been met, the issue

then shifts to whether the expert employed an accepted procedure or tech-

nique and whether an adequate foundation for the admissibility of the pro-

posed evidence has been established.

Opinion evidence must be based on facts in the record or personally

known to the witness. An expert witness cannot reach a conclusion by

assuming material facts not supported by the evidence. The underlying

assumption of virtually all the cases dealing with expert testimony is that

the jury must know the facts upon which the expert bases his or her opin-

ion in order to evaluate the value of that opinion.

1 293 F. 1013 (D.C. Cir. 1923).

§ 10.1FOUNDATION EVIDENCE, 5TH ED.

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[10.1] II.FORMAL OFFER OF WITNESS AS EXPERT

New York law does not require that the party formally request the court

to declare the witness as an expert after his or her background and qualifi-

cations have been explained, nor that the court declare the expert witness

as such before an opinion is elicited.2 Only when, and if, the opposing

party challenges the expert’s credibility and qualifications must the court

make such a determination.

Nevertheless, most attorneys prefer to formally offer their expert wit-

nesses to the court for qualification upon completing their foundation

examination for two practical reasons: (1) to avoid interruption of the sub-

stantive questioning and (2) for the added effect it may have on the jury

when the judge rules that the witness may testify as an expert. However,

some courts will not agree to a judicial qualification at this juncture and

will address that issue only when the opposing party objects to the expert

witness’s opinion testimony. The foundation questions outlined in the last

part of this chapter for various types of expert witnesses avoid interrup-

tions in the narrative and are therefore preferred.

[10.2] III.SCOPE OF FOUNDATION QUESTIONS

FOR EXPERTS

In general, certain issues should be explored and resolved before a wit-

ness can be qualified as an expert in a particular discipline, including:

•school(s) attended and any specialized training in the expert’s disci-

pline;

•length of time spent working in the field;

•familiarity with literature on the subject;

•teaching experience;

•whether the witness has authored any books or articles;

•membership in professional organizations relating to the discipline;

•prior and current employment;

2 People v. Gordon, 202 A.D.2d 166, 167, 608 N.Y.S.2d 192 (1st Dep’t 1994) (“There is no require-

ment that a trial court formally ‘certify’ a witness as an expert (seeUnited States v. Bartley, 855

F.2d 547, 552).”).