Encyclopedia of Psychology and Law

Research has also shown that there have been rela-

tively few changes in the admission rates for expert

testimony post-Joiner and Kumho.Admission rates

remained the same for experts in both civil and crim-

inal cases. However, research has shown that admis-

sion rates for scientific expert testimony have actually

increased post-Kumho, which suggests that judicial

review of scientific testimony became less stringent

while preserving judges’ previous approach to deter-

mining the admissibility of other types of expert testi-

mony. Other research has suggested that no effect for

Kumhowas seen because judges had already started

judging nonscientific expert testimony on the basis of

reliability before the decision was handed down.

Therefore,Kumhoaffirmed the practice of gatekeep-

ing for nonscientific expert testimony that many

judges had already assumed, without a negative

impact on the admission rates for expert testimony.

Ryan W. Copple, Jennifer M. Torkildson,

and Margaret B. Kovera

See also Expert Psychological Testimony; Expert

Psychological Testimony, Forms of

Further Readings

Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993).

Dixon, L., & Gill, B. (2002). Changes in the standards for

admitting expert evidence in federal civil cases since

the Daubert decision. Psychology, Public Policy, & Law,

8,251–308.

Faigman, D., & Monahan, J. (2005). Psychological evidence

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

Psychology, 56,631–659.

Frye v. United States, 293 F. 1013 (D.C. Cir. 1923).

General Electric Co. v. Joiner, 522 U.S. 136, 118 S. Ct. 512

(1997).

Groscup, J. L. (2004). Judicial decision-making about expert

testimony in the aftermath of Daubertand Kumho.

Journal of Forensic Psychology Practice, 4,57–66.

Groscup, J. L., Penrod, S., Huss, M., Studebaker, C., &

O’Neil, K. (2002). The effects of Daubert v. Merrell Dow

Pharmaceuticalson the admissibility of expert testimony

in state and federal criminal cases. Psychology, Public

Policy, & Law, 8,339–372.

Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999).

Youngstrom, E. A., & Busch, C. P. (2000). Expert testimony

in psychology: Ramifications of Supreme Court decision

in Kumho Tire Co., Ltd. v. Carmichael. Law and Ethics,

10,185–193.

EXPERTPSYCHOLOGICAL

TESTIMONY, FORMS OF

Expert evidence comes to court in a variety of forms

and, in particular, at a couple of levels of generality. It

often involves general research findings that, although

relevant to a particular case, also transcend that case.

General research findings will sometimes be used in

the establishment of applicable law and decided by

judges but, more typically, will be considered a com-

ponent of the fact-finding duties of triers of fact. A

large part of expert evidence, however, involves fac-

tual issues that are specific to particular cases, though

they may be claimed instances of more general phe-

nomena. Courts and scholars have proposed various

models to account for the several ways in which

expert evidence is manifested in court. The three most

influential of these models are considered here.

To be admitted, expert opinion must be relevant to a

material fact in dispute. This basic requirement ties prof-

fered expertise to the substantive law of the case. Hence,

for example, if applicable law requires that a substance

be proven to have causedthe plaintiff’s injury, expert

proof regarding causation will be relevant; and if this

proof is reliable and valid, it will usually be admitted.

But proving simple causation of this sort can be a com-

plicated matter. The plaintiff must first prove that the

substance in question sometimes doescause the injury

and, moreover, that it didcause the injury in this case.

As this example illustrates, the facts in dispute in a legal

case can appear at a couple of levels of generality. This

fact has great relevance both to how and whether experts

testify and the procedural legal response to proffers of

different forms of expert opinion.

The recognition that facts arrive in court in different

forms has spawned several scholarly attempts to impose

some schematic theme on them. Three frameworks, in

particular, have received considerable attention and are

discussed below. These are (1) Kenneth Culp Davis’s

distinction between legislative facts and adjudicative

facts; (2) John T. Monahan and Laurens Walker’s three-

part division of social authority, social frameworks, and

social facts; and (3) post-Daubertcourts’ differentiation

between general causation and specific causation.

The Davis Model

In 1942, Kenneth Culp Davis identified two basic

kinds of facts having evidentiary significance—what

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