FBI Admits Pseudoscientific Hair Analysis Used in Hundreds of Cases

Nearly 3,000 cases included testimony about hair matches, a technique that has been debunked

Hair Evidence
Rafe Swan/Corbis

In what The Guardian has called a “judicial catastrophe” of epic proportions, the FBI and Justice Department have admitted that in over 95 percent of trials revisited in a historic review, agents gave flawed testimony based on the pseudoscience of hair analysis.

Spencer S. Hsu at The Washington Post broke the story late last week, reporting that the extent of the problem was unveiled during a review of thousands of cases in which forensic testimony led to a conviction. These included 268 trials that incorporated microscopic hair analysis, a pseudoscientific technique in which forensic experts use microscopes to “match” hairs found on crime scenes to defendants.

Hair analysis has been in use since the 1850s, reports Ed Pilkington at The Guardian, citing a study that traces the technique’s evolution “from magic to law.” The practice is based on erroneous claims that an individual’s hairs can be reliably matched to them. But the technique is based on visual analysis, not DNA, Pilkington explains, using the case of George Perrot, a man convicted of rape solely on hair analysis as an example:

Over the past few years, advanced understanding in the science of hair types has left hair analysis, as a forensic tool, in tatters. Today’s consensus by real experts is more straightforward than ever: there is nothing that can credibly be said, by FBI-approved analysts or anyone else, about about the frequency with which particular characteristics of hair are distributed in the human population.

In other words, microscopic analysis of hair – the very analysis that put George Perrot and so many people behind bars – is virtually worthless as a method of identifying someone. It can only safely be used to rule out a suspect as the source of crime-scene materials or in combination with the vastly more accurate technique of DNA testing.

Bad science has put people behind bars before. For example, long-held arson investigation techniques are now being challenged by advances in fire science. A checklist of traits about a sex-offender's past often used to keep them in jail longer has recently been questioned by scientists. Bite marks have been used to convict people, and even fingerprint analysis has been called into question. 

Questions persist about the extent of the use of hair analysis in the courtroom — and why it took so long to uncover. “While the FBI and DOJ are to be commended for bringing these errors to light and notifying many of the people adversely affected,” says The Innocence Project co-director Peter Neufeld in a release, “this epic miscarriage of justice calls for a rigorous review to determine how this started almost four decades ago and why it took so long to come to light.”

Right now, only 268 of around 2,500 cases involving hair analysis have been reviewed thus far in this investigation, so there's no telling just how many people hair analysis has falsely convicted just yet. In at least 35 of those cases, the defendents were sentenced to death. Nine of those people have been executed, and five have died while on death row.

Experts hope the new revelations will be paired with changes in the ways in which forensics experts both operate and testify in court. This, of course, is cold comfort for defendants who may have been wrongfully convicted or executed at the hands of pseudoscience.  

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