Hair tests, bite marks, blood spatter: it’s mostly magic.
In April 2015, the FBI made an admission that was nothing short of catastrophic for the field of forensic science. In an unprecedented display of repentance, the Bureau announced that, for years, the hair analysis testimony it had used to investigate criminal suspects was severely and hopelessly flawed.
The Innocence Project’s M. Chris Fabricant and legal scholar Tucker Carrington classify the kind of hair analysis the FBI performs as “magic,” and it is not hard to see why. By the Bureau’s own account, its hair analysis investigations were unscientific, and the evidence presented at trial unreliable. In more than 95 percent of cases, analysts overstated their conclusions in a way that favored prosecutors. The false testimony occurred in hundreds of trials, including thirty-two death penalty cases. Not only that, but the FBI also acknowledged it had “trained hundreds of state hair examiners in annual two-week training courses,” implying that countless state convictions had also been procured using consistently defective techniques.
But questions of forensic science’s reliability go well beyond hair analysis, and the FBI’s blunders aren’t the only reason to wonder how often fantasy passes for science in courtrooms. Recent years have seen a wave of scandal, particularly in drug testing laboratories. In 2013 a Massachusetts drug lab technician pled guilty to falsifying tests affecting up to 40,000 convictions. Before that, at least nine other states had produced lab scandals. The crime lab in Detroit was so riddled with malpractice that in 2008 the city shut it down. During a 2014 trial in Delaware, a state trooper on the witness stand opened an evidence envelope from the drug lab supposedly containing sixty-four blue OxyContin pills, only to find thirteen pink blood-pressure pills. That embarrassing mishap led to a full investigation of the lab, which found evidence completely unsecured and subject to frequent tampering.
There have also been scores of individual cases in which forensic science failures have led to wrongful convictions, the deficiencies usually unearthed by the Innocence Project and similar organizations. In North Carolina, Greg Taylor was incarcerated for nearly seventeen years thanks to an analyst who testified that the blood of a murder victim was in the bed of his truck. But later investigation failed to confirm that the substance was blood, or even of human origin. Forensics experts have used “jean pattern” analysis to testify that only a certain brand of blue jeans could leave their distinctive mark on a truck, as occurred in the trial of New Yorker Steven Barnes, who spent twenty years in prison for a rape and murder he didn’t commit.
Some wrongful convictions can never be righted—for example, that of Cameron Todd Willingham, who was convicted by a Texas court of intentionally setting the fire that killed his three young daughters. After the state executed Willingham, an investigative team at the Texas Commission on Forensic Science concluded that the arson science used to convict him was worthless, and independent fire experts condemned the investigation as a travesty. But those findings came too late to do Willingham any good.
The mounting horror stories, and the extent of corruption and dysfunction, have created a moment of crisis in forensic science. But the real question is not just how serious the problems are, but whether it is even possible to fix them. There are reasons to suspect that [ … ]