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Why Some Forensic Evidence Isn't Accurate Or Reliable05:53

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This April 17, 2013 photo shows dental molds used for research at the University of Buffalo, N.Y. Bite mark evidence that may connect a murder suspect to the victim will be allowed at trial, a judge in New York City decided Sept. 5, 2013, disappointing those who hoped the case would help get the forensic technique banished from the nation's courtrooms.  (David Duprey/AP)closemore
This April 17, 2013 photo shows dental molds used for research at the University of Buffalo, N.Y. Bite mark evidence that may connect a murder suspect to the victim will be allowed at trial, a judge in New York City decided Sept. 5, 2013, disappointing those who hoped the case would help get the forensic technique banished from the nation's courtrooms. (David Duprey/AP)

This month, the National Commission on Forensic Science is pressing the Justice Department to look into ways to improve forensic science standards and how forensic evidence is used by law enforcement and in court.

Peter Neufeld, co-founder and co-director of the Innocence Project, explains the problems with certain types of forensic evidence to Here & Now's Peter O'Dowd.

Interview Highlights: Peter Neufeld

On the unreliability of hair matching techniques

“Well, we’re not talking about a DNA test. We’re talking about a technology which the FBI and state and local crime laboratories across the country have relied upon to associate an accused to a piece of crime scene evidence for the last 40 years by looking at hairs under a microscope that they found in a crime scene and comparing it to a defendant’s hair. It turns out that for 30 or 40 years, they were exaggerating the probative value of those similarities such that in, I would say a quarter, of all the DNA exoneration cases, the people were originally convicted in part based on crime lab people coming in and saying the hairs matched.”

On the unreliability of bite marks

“With bite marks, they don’t have a means of determining whether or not the impression left on the skin is similar to the impression of an accused, and the problem is that skin, as you know, moves. So let’s say that you bit me in five different places and two of those times I was stationary and three times I was twisting my body, none of those impressions would look similar. The details in the bite mark are more often than not so few that when you say that it’s consistent with this particular suspect, well it may be consistent but it might be consistent with thousands or tens of thousands of other men.”

Whether this evidence should be included in cases anyway

“Science is science. Either you have the data that supports your conclusion or you have a hunch. It’s that simple. And unfortunately, a lot of these people that had the best of intentions nevertheless lacked scientific rigor and they would offer conclusions that were simply not supported by science but because they were well-intentioned and because they had done them for 20 years, juries believed them.”

On whether DNA evidence is the gold standard

“Nothing is completely rock solid that involves human beings conducting a test. There’s always the potential for human error. But certainly DNA, unlike many other disciplines, had a long history in medicine ever before it was used in criminal justice. And with that kind of background, it made it much easier to have reliable DNA testing for crime scenes. Not so with those other disciplines which were never developed for medicine, but were developed by law enforcement, for law enforcement.”

On what the criminal justice system should aspire to

“What you want to do in the criminal justice system is ultimately develop the most scientifically rigorous, reliable methods so we can all get to the truth and victims can be more satisfied, defendants can be more satisfied and the public can rest assured that we reached the right result.”

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