Judges Need to Set a Higher Standard for Forensic Evidence
The National Commission on Forensic Science was formed in response to widespread concerns that forensic evidence that lacked any meaningful scientific basis was being regularly permitted in trials. The concerns were not just about the “expert” witnesses, but about the judges who, according to the National Academy of Sciences report that led to the commission’s creation, have been “utterly ineffective” in assessing the quality of research behind the evidence.
The evidence used to win convictions has often been based on bad science. In about half of the cases in which D.N.A. evidence led to exoneration, invalid or improper forensic science contributed to the wrongful conviction.
Appeals courts almost invariably affirm trial judges’ admission of evidence that has been challenged, unless the judge abused his or her discretion by, in the words of one ruling, making a decision that “no conscientious judge, acting intelligently, could honestly have taken.” That’s hardly a strict standard.
Sadly, judges are more likely to reject scientific evidence in civil cases, in which both sides can have substantial resources, and in which there is a discovery process that enables each side to find out about the other’s case far in advance of trial. In an arson case I presided over as a judge, I could find no criminal cases in which there had been a challenge to the admissibility of evidence from dogs who supposedly could sniff out fire-spreading fuels.
The national commission is doing more than exhorting judges to do the right thing, which sadly did not get very far. It is bringing together representatives of the Department of Justice, the National Institute of Standards and Technology, defense lawyers and experts to set standards for judges, and prosecutors, to follow. If the Justice Department doesn’t try to admit evidence of questionable validity, then state and local prosecutors may follow suit. That could go a long in solving the problems with forensic science.