Commonwealth v. Walker
625 Pa. 450
| Pa. | 2014Background
- Appellant Benjamin Walker was tried for two October 2005 armed robberies; convictions rested solely on eyewitness identifications from photo arrays and a lineup.
- Walker sought to present Dr. Solomon Fulero as an expert on eyewitness perception/memory (weapons focus, cross-race effect, stress, suggestive ID procedures, confidence vs. accuracy) and alternatively requested a Frye hearing on that testimony.
- Trial court excluded the expert (relying on Pennsylvania precedent that categorically bars eyewitness-identification experts), tried the consolidated case, acquitted on one incident and convicted on the other; sentence imposed.
- Superior Court affirmed based on binding Pennsylvania precedent (Spence, Simmons, Abdul‑Salaam) that such expert testimony impermissibly invades the jury’s credibility function.
- The Pennsylvania Supreme Court granted allowance to reconsider whether expert testimony on eyewitness identification may be admitted in the trial court’s discretion and whether a Frye hearing is warranted.
Issues
| Issue | Walker's Argument | Commonwealth's Argument | Held |
|---|---|---|---|
| Admissibility of expert testimony on eyewitness identification | Expert testimony explaining scientific factors (weapons focus, cross‑race effect, stress, suggestive procedures, confidence/accuracy) is generally accepted in the relevant scientific community and would assist jurors in evaluating IDs | Such testimony improperly invades the jury’s province on credibility, is unfairly prejudicial, may make jurors skeptically discount all IDs, and cross‑examination/closing argument suffice | Overruled Pennsylvania’s categorical ban; court held such expert testimony is not per se inadmissible and may be admitted at the trial court’s discretion if Rule 702 (including Frye) and Rules 401/403 are satisfied |
| Applicability of Frye and standard for admissibility | If proffered methods are generally accepted, testimony should be admitted; Frye hearing requested | Even if literature exists, such evidence is prejudicial or not helpful; Frye not implicated | Court remanded for the trial court to reconsider admissibility and to determine (case‑by‑case) whether a Frye hearing is required; Frye remains the gatekeeping test in PA for novel scientific evidence |
| Relevance / Rule 403 (probative v. prejudicial) | Expert evidence is relevant where case hinges on uncorroborated eyewitness IDs and will help jurors assess reliability | Expert testimony tends to unduly prejudice/ confuse jurors and may prompt battles of experts | Court said relevance/probative value must be assessed by trial court; no per se exclusion under Rule 403 — trial judge controls scope and tailoring of testimony |
| Constitutional claim to present a defense via expert | Denial of expert testimony impaired Walker’s Sixth Amendment right to present a defense | Evidentiary rules limit presentation; exclusion was proper under precedential rule | Court did not decide constitutional issue (remanded to allow evidentiary reassessment; declared prior categorical precedent inconsistent with modern approach) |
Key Cases Cited
- Commonwealth v. Spence, 534 Pa. 233 (Pa. 1993) (established prior Pennsylvania bar on expert testimony addressing eyewitness credibility)
- Commonwealth v. Simmons, 541 Pa. 211 (Pa. 1995) (reaffirmed categorical exclusion of eyewitness‑identification experts)
- Frye v. United States, 293 F. 1013 (D.C. Cir. 1923) (test for general acceptance of novel scientific evidence)
- Grady v. Frito‑Lay, 576 Pa. 546 (Pa. 2003) (confirmed Pennsylvania follows Frye standard for novel scientific evidence)
- Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (U.S. 1993) (federal gatekeeping standard; discussed as contrast to Frye)
- Manson v. Brathwaite, 432 U.S. 98 (U.S. 1977) (factors for due‑process review of pretrial identification procedures)
- United States v. Wade, 388 U.S. 218 (U.S. 1967) (recognizing both importance and fallibility of eyewitness ID)
- New Jersey v. Henderson, 208 N.J. 208 (N.J. 2011) (encyclopedic state high‑court review supporting discretionary admission of eyewitness experts)
- State v. Clopten, 223 P.3d 1103 (Utah 2009) (overruled categorical ban; endorsed limited use of experts to educate jurors)