SAN FRANCISCO (CN) – Trial judges should be more skeptical of forensic methods that don’t pass scientific muster, a panel of legal experts told judges at the Ninth Circuit Judicial Conference on Tuesday.
Jennifer Mnookin, dean of the UCLA School of Law, said Tuesday that popular culture, particularly TV shows like “CSI,” have led juries to believe forensic evidence is authoritative and almost always reliable. That simply isn’t true, she said.
“Faulty forensic science is the second most frequently found contributing cause [of DNA exonerations], second only to eyewitness identifications that turn out to be erroneous,” she said.
Forensic techniques like fingerprint identification, bite marks, ballistics, hair and footprint analysis were all called into question in a Barack Obama administration report last year by the President’s Council of Advisors on Science and Technology. It debunked decades of forensic practices, saying evidence needs to be empirically and independently tested multiple times in order to determine its scientific validity.
“It must take scientific study to make a field scientifically reliable,” Mnookin said. “Experience, no matter how extensive, could not be a substitute for scientific study.”
Law enforcement agencies were quick to challenge the PCAST report when it was released this past September, but Tuesday’s panel urged judges to strongly consider the report when deciding whether to admit forensic evidence in criminal trials.
“PCAST was truly directed at the courts,” Los Angeles Deputy Public Defender Jennifer Friedman said. “It was not intended to tell the people in this room how to decide cases, but to discuss and explain the intersection of scientific validity and legal reliability.”
Friedman said a real tension has developed between science and the courts. While science is always looking forward, questioning hypotheses and retesting methods, the courts tend to look backwards at precedent to ensure fairness.
“But we have an opportunity in the courts to drive the science in a direction that many scientists really do want to go,” Friedman said.
One thing judges can do is rein in forensic examiners during testimony.
“Forensic examiners shouldn’t be able to come into court and make claims of 100 percent certainty, or testify that they’ve never made a mistake or that the error rate for the discipline is zero,” Friedman said. “If the courts were to curtail that type of testimony we would go a long way in preventing wrongful convictions and ensure the integrity of the evidence being admitted.”
Ninth Circuit Judge Alex Kozinski said like many judges and others in the legal community, he had long accepted the idea that certain forensic methods were virtually infallible. But he said a 2005 article in Science Magazine made him question his long-held beliefs.
“It went through, step by step, various methods of forensic evidence used in criminal cases and just showed that when you subject them to tests of scientific validity they turn to be doubtful and all the way down to completely useless,” he said. “Bite marks turn out to be completely useless, bullet fragments tend to be highly unreliable. Fingerprints, which I thought were the standard of validity, turn out to have a significant error rate when you test them against unknown samples.”
He added, “The PCAST report addresses some of these issues and I thought it was a step forward in bringing all of us to a conclusion that maybe we need to do a better job, because after all this is not a situation where we’re dealing with just technicalities but we’re dealing with the question of whether people are guilty or innocent.”
Meanwhile, defense lawyers need to start raising concerns about forensic evidence with judges, Kozinski said.
“I think there’s a reluctance to put to the test scientific evidence put on by the prosecution. Many defense lawyers, like the rest of us, grew up with fingerprints, bite marks and footprint evidence and simply accept it as being inherently valid and not worth challenging,” he said. “And if judges don’t have the issue presented, it’s difficult for a judge. Many judges are reluctant to say – if the lawyers don’t raise the issue – have you thought about the scientific validity of this.”
An even bigger problem, Friedman added, was that there aren’t a lot of scientific experts out there who are available or willing to testify.
“It’s challenging to find experts,” she said. “And we don’t always represent the most enviable clients.”
U.S. District Judge Paul Grimm said with the frenetic pace of most cases – between speedy-trial rules, defense attorneys and prosecutors haggling over plea deals and the release of investigative discovery – judges run out of time to set hearings to determine whether forensic evidence should be allowed in.
“As judges, we have to be much more aware of it at the beginning when we’re handling criminal cases and we’re talking about scheduling,” he said. “We need to raise these issues earlier on in the process, against that entire backdrop where there’s this kabuki dance between lawyers trying to see if this case is going to plead or not plead.”
Grimm said the response in the judicial community to the PCAST report parallels the release of the Daubert rules of evidence regarding expert witness testimony.
“It’s not like trial judges got together for a big celebration when Daubert came out,” Grimm said. “I am a judge because I didn’t understand science and math! If I could do science and math, I’d be Doctor so-and-so, not Judge so-and-so. That’s the reaction of judges in terms of dealing with these things. It’s going to take time.”