Contradictory Court Rulings on Expert Witnesses
The Pennsylvania Supreme Court could not make up its mind on the usage of expert testimony in criminal cases, handing down two contradictory decisions recently.
In the first case, on eyewitness testimony, a majority changed the longstanding rule that no experts on the problems with eyewitness testimony were allowed; from this point forward, the Supreme Court ruled, trial courts in PA may permit experts.
But in the other case, the court ruled the exact opposite, stating expert testimony can create a false confession.
Pitt Law Professor David Harris believes he can help clarify the cases.
“The issue in both cases is whether the defense can bring in an expert who would bring the jury scientific and research based information about a crucial aspect of the evidence," said Harris "In one case it was about eyewitness testimony, in another, it was about whether a confession could be a false confession. What are the risk factors for creating false confessions? We know for a certainty that both will generate errors in a certain percentage of cases. We know this because of the hundreds of DNA based exonerations we already have… very few cases have DNA issues in them, but in those cases, 75% of those cases have eyewitness identification mistakes. That really tells you a lot about the frailty of eyewitness identification evidence.”
Harris believes that regardless of the final outcome, the state needs to be preventing these problems before cases enter the courtroom.
“What we should be doing in Pennsylvania is we should be having a deep, long-term discussion about how we change eyewitness testimony practices before a case gets to court. We should move from simultaneous to sequential lineups, lineups where a person is shown individuals or a picture one at a time instead of all together… we got to go to blind lineups, we have to have statements given to the witnesses viewing a lineup that says things like ‘the person who did the crime may not be here’. All of these things are part of the accepted research now.”