In Commonwealth v. Walker, 92 A.3d 766 (2014), the Pennsylvania Supreme Court held expert testimony regarding eyewitness identification may be used in criminal court in Pennsylvania. However, the ruling means the trial judge gets to decide whether to allow the testimony at trial. The standard for the the admissibility is based on something called the Frye standard, which comes from the case, Frye, which was adopted in Pennsylvania in Commonwealth v. Topa, 369 A.2d 1277 (Pa. 1977). In Pennsylvania, we have adopted the Frye standard via statute:
Rule 702. Testimony by Expert Witnesses.
A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if:
(a) the expert’s scientific, technical, or other specialized knowledge is beyond that possessed by the average layperson;
(b) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue; and
(c) the expert’s methodology is generally accepted in the relevant field.
The reason this topic is relevant is often eyewitnesses witnesses make mistakes when making an identification, making their testimony somewhat unreliable. However, lawyers are not allowed to argue the unreliability of eyewitness identification, specifically cross racial identification. Lawyers and witnesses are never allowed to give their opinion about the testimony of other witnesses, unless of course, they themselves are an expert in the field. Previous to Walker, in Pennsylvania, expert testimony on eyewitness identification was per se not allowed because Pennsylvania did not recognize eyewitness identification as a scientific field even though the majority of states in the United States had recognized such a field of expertise.
After Walker was decided, the PA Supreme Court sent the case back to Philadelphia for the judges to determine if, after a Frye hearing, Rule 702 was met, and therefore allow expert testimony on eyewitness identification. A Frye hearing was held in late 2014 through early 2015 in Philadelphia based on the decision from the Pennsylvania Supreme Court. On March 20, 2015, the three judge panel unanimously ruled expert testimony on eyewitness identification is admissible under Frye and expert science exists on eyewitness testimony. However, the Court ruled with no blanket decision. Rather, the ruling states that in each case, every judge should consider the factors and make their own ruling on the admissibility of expert testimony on eyewitness identification.