When the Innocence Project reviewed the files of 310 people who have been exonerated of criminal convictions through DNA evidence, it noticed a disturbing trend. 72 of them had been convicted, in part, because of apparently misleading testimony by FBI hair sample analysts. Some of them died in prison before their innocence could proven.
Those errors have prompted the Justice Department to initiate an unprecedented review of some 2,000 cases in which FBI analysts testified about hair-sample DNA between 1985 and 2000. Many involve convictions for violent crimes or murder, including death penalty cases. It has even agreed to waive appellate deadlines and procedural hurdles in these cases. "This will be critical to giving wrongly convicted people a fair chance at a fair review," said a spokesperson for one of the groups seeking the review.
During the review period between 1985 and 2000, hair sample analysis was not as sophisticated as it is today. Even now, of course, all scientific testimony is open to question by the defense because it is performed by humans, and humans make mistakes. They may also overestimate the reliability and importance of the science they perform, either through prosecution bias or simply due to overconfidence. Even if the science itself is valid and performed correctly, there is a possibility that a lab technician's testimony may overstate the significance of the findings and thereby prejudice the jury.
According to the request for the review, the problem here appears to be a pattern of expert witnesses overestimating the significance of their findings when early hair sample analysis was performed, misleading jurors into believing the presence of a certain hair sample at a certain crime scene was definitive -- when scientifically speaking it was not.
"The government's willingness to admit error and accept its duty to correct those errors in an extraordinarily large number of cases is truly unprecedented," says a co-director of the Innocence Project. "It signals a new era in this country that values science and recognizes that truth and justice should triumph over procedural obstacles."
When someone is accused of a heinous or violent crime, many jurors -- and members of the public -- can be shocked by the allegations themselves. It's crucial to ensure that all of the facts are presented in an atmosphere of reason and scientific honesty, or the horror of the merely alleged offense can translate virtually directly into a conviction.
Source: Star-Telegram, "FBI announces review of 2,000 cases featuring hair samples," Michael Doyle, McClatchy Washington Bureau, July 18, 2013