Two conjectures about the issue of expert testimony.

Abstract

This article responds to concerns about expert testimony in experimental psychology by conjectur that disagreements about the propriety of the testimony are camouflaged arguments about the strength of psychological knowledge. Differences between proponents and opponents of expert testimony are about the state of psychological knowledge and certainty, rather than about the proper standard for psychologists to use when deciding whether to testify. A second conjecture is stimulated by the assumption that laypersons generally overvalue eyewitness testimony and that expert psychological testimony is a required corrective. The truth of this assumption rests on the debatable assertions that eyewitness identifications, without more, are potent sole determinants of trial outcome, and that lay juries need instruction from experimental psychologists about aspects of human behavior of which the jurors are definitive producers and consumers. One need not resolve these debates in order to understand that psychologists should not rely on the legal community to set the psychologists' standards for expert testimony. And psychologists, in considering their role as courtroom experts, should guard against a self-serving critique of the acumen of lay juries.