Pennsylvania Supreme Court Removes Ban


On July 15th, 2014 the Pennsylvania Supreme Court removes the ban on expert testimony about eyewitness unreliability.

In an exciting development in criminal trial practice, a divided Pennsylvania Supreme Court has reversed its prior precedent and removed its 20 year prohibition on expert testimony regarding eyewitness identifications. Prior to this ruling, there was an absolute ban in this state on expert testimony about the reliability of eyewitness testimony. Following the lead of nearly all the federal circuit courts, 44 other states, and the District of Columbia, Pennsylvania will now allow an expert witness to tell jurors about the decades of research into the reliability of eyewitness testimony.

The case, Commonwealth v. Walker, arose from the conviction of Benjamin Walker for robbery of two college students in Philadelphia. The prosecution’s case against Walker was primarily based on eyewitness testimony. Walker’s attorneys challenged his conviction on the grounds that the trial court denied his request to present an expert witness who would explain to the jury that eyewitness testimony is often inaccurate. That request was denied due to the long-standing precedent in this state that such testimony is per se inadmissible.

Twenty years of advances in scientific study have strongly suggested that eyewitnesses are apt to erroneously identify a person as a perpetrator of a crime when certain factors are present.

After revisiting that precedent in Walker’s appeal, the Pennsylvania Supreme Court decided to join the vast majority of other courts in admitting expert testimony to help the jury understand eyewitness testimony and make more accurate and just determinations. The majority in Walker wrote, “Twenty years of advances in scientific study have strongly suggested that eyewitnesses are apt to erroneously identify a person as a perpetrator of a crime when certain factors are present.” Given the fact that juries place a high value on eyewitness testimony, sometimes to the exclusion of all other evidence, it is important that the jury be informed that in many circumstances, eyewitness identification is inaccurate and untrustworthy.

While the Court’s ruling is certainly promising for many criminal defendants, it must be noted that expert testimony about eyewitness identification will not be permissible in every case. The decision to allow such testimony will be within the trial judge’s discretion. Among the trial judge’s considerations in allowing expert testimony about the fallibility of eyewitness testimony is whether the testimony is relevant and helpful for the jury to make an informed decision. The Court did not specifically define the types of cases in which such testimony would be permissible, but the Court did suggest that it would most often be relevant in situations where the Commonwealth’s case is dependent upon eyewitness testimony. Furthermore, the expert must still be qualified to provide expert testimony and the testimony must be based on scientifically valid principles. Importantly, the expert is NOT permitted to testify about whether a specific eyewitness in the case is reliable, but rather is only permitted to explain the scientific findings about eyewitness accuracy and the general fallibility of human recollection.

This ruling marks a dramatic shift in the way Pennsylvania courts handle criminal cases based on eyewitness identifications. Most significantly, the decision has the potential to reduce the number of innocent people convicted of crimes, because inaccurate eyewitness identification is one of the leading causes of wrongful convictions. By removing the ban on expert testimony about the reliability of eyewitness testimony, the Pennsylvania Supreme Court has taken an important step in preventing wrongful convictions, which represent one of the gravest concerns of our legal system.

To speak with an experienced criminal law attorney, please contact The Masorti Law Group at (814) 234-9500.