Expert Testimony: Legal Standards for Admissibility

The determination of whether to admit expert testimony on eyewitness perception, retention, and recall is not in any way limited to questions of science. Rather, it is a product of a series of factors: what expert testimony test (Frye or Daubert) the jurisdiction applies; the facts of the particular case; and the vast discretion accorded to trial judges in making admissibility decisions. While the majority of courts have found the scientific underpinnings of this proposed testimony sufficient to meet the varying admissibility standards, in any specific case there is no guarantee that such proof will be admitted. In each case, the question of admissibility will turn on the perceived importance of the evidence (often weighed against the presence of corroborating proof of guilt); the sufficiency of the expert's credentials/experience and of the offer of proof; and whether the testimony has “fit,” i.e., relevance to the particulars of the case. Finally, even if admissible, a trial court may restrict the scope [breadth] of the expert's testimony.