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Judging the Evidence

CONVICTING CRIMINALS on television shows is often a breeze, thanks to forensic science. In the real world, it has never been that easy—and it’s likely to get even harder if judges start putting forensic practices themselves under the microscope. Critics who say forensic evidence has been oversold have pushed for that to happen, and now, at least one judge has taken a proactive stand on the issue.

Last year the National Academies of Science (NAS) released a highly publicized report questioning the scientific methodology of many of the forensic sciences that are used as evidence in courtrooms every day. The issue involves everything from how evidence of arson gets interpreted to how certain a jury can be that a fingerprint fragment came from the person charged with the crime. The report found that the only scientifically validated forensic science is DNA analysis. (Read about it in the December 2009 issue of Security Management).

In response to the report, U.S. District Court for Massachusetts Judge Nancy Gertner issued a procedural order on trace evidence earlier this year. She cited the report’s highlighting of fundamental questions regarding the extent to which certain evidence is scientifically valid and the extent to which forensic practitioners rely on expert interpretation that could be biased or errorprone. Gertner urged prosecutors and defense lawyers to take the various evidence statutes and admissibility hearings seriously and warned attorneys not to expect evidence to be admitted simply because it traditionally has been.

Simon Cole, criminology, law, and society professor at the University of California, Irvine, says that some judges and litigants have contended that the various evidentiary hearings cited by Gertner do not apply to certain types of evidence and that hearings are not needed in those cases for any number of reasons, including the fact that the sciences are not new. Cole says Gertner’s order appears to be designed to clearly reject those notions.

It is unusual for judges to be proactive in this way, says David Faigman, law professor at the University of California’s Hastings College of the Law. Faigman adds, “It’s about time.” Faigman has written about the lack of scientific validation for commonly accepted techniques like latent fingerprint analysis.

Although many people assume that fingerprint evidence is airtight, it should be noted that such evidence is rarely perfect. Often only a small trace has been left behind and that fragment may not be good enough to produce a high-quality latent print. Given the meager bit they work with, experts can get it wrong when they do their analysis, as occurred in the 2004 Madrid train bombing case where the FBI mistakenly deemed that the fingerprints in the case matched that of an Islamic lawyer in Oregon named Brandon Mayfield, who was wrongfully arrested for the bombing.

Judge Gertner’s order does not just send a message to prosecutors. It is also directed at defense attorneys, explains D. Michael Risinger, law professor at the Seton Hall University School of Law. He says the order means defense attorneys will have to research the evidence they are refuting and present their own witnesses at trial.

Joseph Bono, president of the American Association of Forensic Scientists and forensic sciences professor at Purdue University, agrees that some forensics are oversold. For example, he notes, “The conclusion that a lot of people are saying right now, or making, is that a particular print came from one person to the exclusion of everybody else. That statement’s been made for a number of years. I think we have to look at that again.”

At the same time, he says the legal system should not throw out the baby with the bath water. For example, in the Mayfield case, a better version of the fingerprints did lead international authorities to the actual perpetrators in the end. Rather than ditching forensic evidence, Bono suggests improvements that can strengthen the field, such as coming up with thresholds for assessing the amount and quality of a latent fingerprint before drawing a conclusion. That tracks with the thrust of the NAS report, which included recommendations for developing forensic science standards, certifications for testers and labs, and oversight.

Faigman says he thinks Gertner may be “at the vanguard of what I would expect to be a movement that will pick up momentum over time.”

Risinger isn’t so sure. There are many reasons why judges might not want to issue orders like this or encourage the hearings that Gertner cites in her order, he says. “They are skeptical of challenges to prosecution-proffered experts and challenges to the reliability of various forensic disciplines,” says Risinger, adding that many judges are ex-prosecutors who themselves used this type of evidence. “Think about the psychological position that puts you in—what you used to convict people 20 years ago really wasn’t as reliable as you thought it was,” he says.