Commonwealth v. Walker

Supreme Court of Pennsylvania · 2014 · Evidence

625 Pa. 450 (2014)

Updated August 22, 2026

EvidenceExpert testimonyEyewitness identificationFryePa.R.E. 702general acceptancerelevanceRule 403

Facts

The Commonwealth's case connecting Walker to the October 28, 2005 robbery rested solely on eyewitness identifications by the two victims. Before trial, Walker sought to present Dr. Solomon Fulero as an expert on the fallibility of human memory and scientific research concerning eyewitness reliability, or at least to obtain a Frye hearing on that evidence. He identified topics including weapons focus, cross-racial identification, stress effects, the risk created when witnesses are not told the perpetrator may or may not be in the array, and the weak correlation between confidence and accuracy. The trial court denied both requests under existing Pennsylvania precedent that treated expert testimony on eyewitness identification as inadmissible.

Issue

Whether a Pennsylvania trial court may, in its discretion, admit expert testimony concerning eyewitness identification, or whether such testimony remains categorically inadmissible. Embedded in that question is whether such testimony improperly invades the jury's credibility function.

Rule

Expert testimony regarding eyewitness identification is no longer per se impermissible in Pennsylvania. Its admissibility is committed to the trial court's discretion and depends on the ordinary requirements for expert evidence: the witness must be qualified, the subject must be beyond the knowledge of the average layperson, the testimony must help the trier of fact, the methodology must satisfy Frye when applicable, and the evidence must be relevant and survive Rule 403 balancing. The defendant must make an on-the-record detailed proffer explaining precisely how the expert testimony relates to the eyewitness identifications at issue and how it will assist the jury.

See the holding & full analysis

Create a free KwikCourt account to unlock the rest of this brief — and practice the case.

The court's holding and reasoning
Doctrine tests, pitfalls & exam hypotheticals
10 practice questions + 4 AI-graded essays on this case

Free sample · practice this case

Test yourself

One of 10 multiple-choice questions for this case. Pick an answer to see why.

In Pittsburgh, Malik Turner is charged with robbery. The prosecution's case depends almost entirely on two stranger identifications made after a late-night street encounter, and Malik seeks to call Dr. Elena Morris, a qualified psychologist, to testify generally about weapons focus and the weak correlation between witness confidence and accuracy, without opining on whether either witness is correct.

How should the trial court rule on the prosecution's argument that such testimony must be excluded because eyewitness-reliability experts are categorically barred and would invade the jury's role?

Explanation. The governing rule is that Pennsylvania no longer applies a per se exclusion to expert testimony regarding eyewitness identification. Such evidence is not automatically admissible, but neither is it categorically barred. The trial court must exercise discretion under Pa.R.E. 702, Frye when applicable, and Rules 401 and 403. The majority also rejected the idea that this type of testimony necessarily invades the jury's credibility role when the expert educates the jury about general psychological principles rather than opining on whether a particular witness is truthful or accurate.