Koehler Investigates Lack of “Science” in Forensic Science
By Rob Meyer
Don’t believe everything you see on CSI.
That was the message delivered by Jay Koehler in his presentation for the Faculty Research Speaker Series March 27.
Actually, Koehler is more concerned with the work of real-life forensic scientists than with the fictional ones found on the hit CBS television franchise.
“Forensic science isn’t quite as scientific as most of us have been led to believe,” said Koehler, a professor in the Department of Information, Risk, and Operations Management.
Video: Watch Prof. Koehler's Faculty Research Series presentation on forensic science. (wmv)
Except for DNA evidence, which has been shown to be highly accurate, the range of other forensic evidence that is routinely brought into the courtroom—such as fingerprints, hair samples, bite marks and tire tracks—has not been nearly as good, Koehler said. In fact, Koehler introduced a study of post-conviction DNA exonerations showing that bad forensic evidence—either from poor analysis or outright fraud—was common and second only to false eyewitness testimony as a factor leading to wrongful convictions.
“Forensic scientists who testify at trial are prone to exaggerate their evidence,” he said. “And we don’t know too much about the error rates in the forensic sciences, but what we do know is quite worrisome.” Not introducing information on error rates into the process is a major problem for the forensic field, Koehler said.
Without error rates, Koehler said “the central assumption in forensic science is flawed.”
Koehler used as an example a murder caused by a hammer to the head. If forensic scientists find a hammer that matches the mark on the head, they conclude it is the murder weapon. It may be an exact match, but they make the leap that it is the only possible match.
“The central assumption in forensic science is that two indistinguishable marks must have been produced by a common source,” said Koehler, a notion he termed “discernable uniqueness.” “That one and only one object could have made that mark. That’s a pretty major assumption.”
Fingerprints are commonly thought of as unassailable evidence. Yet Koehler pointed to studies that showed just how subjective the analysis can be. Different examiners often reach different conclusions when deciding whether a print is a match or not. Koehler stressed the need for introducing error rates into the courtroom testimony. “That is something a jury needs to hear,” he said.
Overall, it is important that the forensic science industry opens up and works to set standards for training, proficiency testing and courtroom presentations.
The good news is that they are beginning to do just that. The DNA-testing field, which came together to work out standards and procedures for the profession, has provided an example for forensic scientists to follow.
“They are doing things right in the world of DNA,” Koehler said. “And they are not doing things right yet at least in the world of traditional forensic science. But they are improving….and forensic science essentially is starting to earn the second word in its title. Until now, it hasn’t really been much of a science.”
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