Forensic Science: A Time of Transformation

For those in the criminal justice system who like certainty, it was a rough week at the American Academy of Forensic Sciences (AAFS) Annual Scientific Meeting in Las Vegas. The February 2016 conference, themed “Transformation: Embracing Change,” reflected the current turmoil in the forensic, legal and law enforcement communities over the roles of science and forensic science and the certainty of evidence presented in the courtroom.

Speaking at a session on jurisprudence, Linda Chezem, a Purdue University professor and retired Indiana state appeals court judge, noted that scientific ethics, particularly forensic science ethics, do not square neatly with the “rule-of-law” ethic of the courtroom. Lawyers do not understand science, and scientists do not understand the law, the former judge observed. Overseeing this conflict are judges who are often “science phobic,” she said, including herself in that group. And as forensic science becomes more and more complex, resolving forensics-based disputes in the courtroom is becoming increasingly difficult, she said.

Another session at AAFS saw Henry Swofford, chief of the Latent Print Branch at the U.S. Army Criminal Investigation Laboratory at the Defense Forensic IT Science Center, warn against using latent fingerprints to definitively identify an individual. He cited one of the center’s recent information papers that discusses the “growing debate among the scientific and legal communities” regarding the use of the terms “identification” or “individualization” in court to associate “an item of evidence to a specific known source.”

“Central to the debate,” the paper says, “is that these terms imply absolute certainty of the conclusion of the fact-finder which has not been demonstrated by available scientific data.” The paper calls for latent print experts to use a “more scientifically appropriate framework for expressing source associations.” When testifying, the paper says, stay away from specific “identification” and instead use this “recommended” language: “The likelihood of observing this amount of correspondence when two impressions are made by different sources is considered extremely low.”

The center’s recommendation reflects a broader “lack of certainty” problem that is affecting virtually all of the non-DNA forensic evidence fields, says David Stoney, former director of forensic sciences at the University of Illinois. Stoney, who now heads Stoney Forensic, Inc., in Chantilly, Virginia, is sympathetic to the dilemma this scientific transition is causing for veteran forensics experts.

“Examiners in some forensic science disciplines have been trained that if you aren’t certain about your result, you don’t say anything,” Stoney says. “It’s your professional reputation every time you go into court and you’ve got this great responsibility. It’s your job as, say, a latent print examiner to only provide an opinion when you are absolutely sure. That’s historically been part of the quality control of the system.”

But in the wake of the 2009 National Academy of Sciences report Strengthening Forensic Science in the United States: A Path Forward, that has changed. Many courts no longer accept the “absolutely sure” quality control system, Stoney says, and instead, “we want to have methods to measure the best that we can, and if we don’t have those, we want people to say they don’t know.”

From a purely scientific perspective, where nothing is known with absolute certainty, that may be proper. But for many veteran fingerprint or firearms experts, this less-than-certain approach is a problem.

“These people have been trained another way, and some view this effort as ‘You’re asking me to do a less competent job, because you’re asking me to pretend I’m uncertain when I’m certain, and you’re asking me to testify when I’m not certain. It isn’t fair. You’re undermining my profession,'” Stoney says. “It’s not an ego thing; it’s changing to a completely different paradigm.”

The certainty issue is more than theoretical, as was made clear in a recent opinion written by a District of Columbia Court of Appeals judge in connection with a homicide case. A firearms expert testified in the case that there was a “unique” match between bullet slugs recovered from the victim’s car and a handgun found in the suspect’s bedroom. The judge wrote that to claim a one-to-one match of a bullet to a gun required the “vision of a psychic” and was based on “foundationless faith in what he believes to be true.” The judge concluded that, “to uphold the public’s trust, the District of Columbia courts must bar the admission of these certainty statements. We cannot be complicit in their use.”