Encyclopedia of Psychology and Law

average layperson. Under most modern evidence

codes, the subject need not be entirely “beyond the

ken,” because expert testimony need only “assist the

trier of fact” (and be reliable) to be admitted. Nonetheless,

much psychological expertise has been excluded on

the basis that it simply reflects common sense.

Although courts have become somewhat more recep-

tive to expert testimony regarding the unreliability of

eyewitness identifications recently, it is still looked on

by many courts as only marginally helpful to triers of

fact and largely a waste of the court’s time.

In a third group of cases, the specific import of prof-

fered expert testimony is the credibility of a specific

witness. Today, this evidence is best represented by

testimony regarding the results of polygraph machines.

Surprisingly, perhaps, modern courts do not object to

this evidence on the ground that it invades the province

of the trier of fact. Indeed, courts, including a majority

of justices on the U.S. Supreme Court (United States v.

Scheffer, 1998), have questioned whether this rationale

would be sufficient to exclude a reliable lie detector.

Instead, courts have focused on the lack of demon-

strated reliability of these tests to support exclusion.

Most courts agree that polygraphs are not admissible,

at least absent stipulation of the parties prior to admin-

istration of the test. But their rationale for exclusion—

lack of proven validity—leaves open the possibility

that future tests, such as fMRI, might be admitted if

validity is adequately demonstrated.

David L. Faigman

See also Expert Psychological Testimony; Expert

Psychological Testimony, Admissibility Standards; Expert

Testimony, Qualifications of Experts

Further Readings

Barefoot v. Estelle, 463 U.S. 880, 887 (1983).

Monahan, J., & Loftus, E. F. (1982). The psychology of law.

Annual Review of Psychology, 33,441–475.

Faigman, D. L. (1989). To have and have not: Assessing the

value of social science to the law as science and policy.

Emory Law Journal, 38,1005–1095.

Faigman, D. L, & Monahan, J. (2004). Psychological

evidence at the dawn of the law’s scientific age. Annual

Review of Psychology, 56,631–659.

Special Theme: Expert testimony in the courts: The influence

of the Daubert, Joiner, and Kumho decisions. Psychology,

Public Policy, and Law, 8,180.

United States v. Scheffer, 523 U.S. 303 (1998).

EXPERTPSYCHOLOGICALTESTIMONY,

ADMISSIBILITYSTANDARDS

Expert psychological testimony, like any testimony,

must meet certain criteria or standards for admissibility

before it is allowed into court. Although the admissibil-

ity of expert evidence was initially governed by the gen-

eral acceptance standard set in Frye v. United States

(1923), more recent standards, including the Federal

Rules of Evidence, have shifted focus to an evaluation

of the reliability of the evidence. This entry outlines the

historical changes in admissibility standards, starting

with the Frye decision and the Federal Rules of

Evidence and progressing through a trio of recent

Supreme Court decisions that address the admissibility

of expert evidence. These decisions include Daubert v.

Merrell Dow Pharmaceuticals (1993), which estab-

lished whether the Federal Rules of Evidence super-

seded the Fryestandard when judging the admissibility

of scientific evidence, and General Electric Co. v. Joiner

(1997) and Kumho Tire Company v. Carmichael(1999),

which established the scope of the Daubertdecision.

FFrryyee vv.. UUnniitteedd SSttaatteess

Before the Daubertdecision, most courts insisted that

testimony proffered by an expert be relevant to the triers

of fact and based on generally accepted principals.

Specifically, this meant that the area the expert was tes-

tifying to must result from theory and technique that

have been generally accepted by a scientific community.

This principle was adopted from a District of Columbia

(DC) Court of Appeals ruling that occurred in 1923.

In Frye v. United States(1923), the DC Court of

Appeals issued one of the first decisions governing the

admissibility of expert evidence. When James T. Frye

was on trial for murder in the first degree, the defense

proffered an expert who would testify about a lie detec-

tion test that was based on changes in the examinee’s

systolic blood pressure in response to questions. The

trial court ruled that this expert testimony was inadmis-

sible, and Frye was convicted. In an appeal of his con-

viction, Frye argued that the trial court’s failure to allow

the expert testimony was improper and resulted in his

conviction. The appellate court reexamined the case

and upheld the original verdict, introducing what is

now referred to as the “Fryetest” for the admissibility

of expert evidence. In its decision, the court wrote that

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