By Eric Lichtblau, New York Times
WASHINGTON — The Justice Department, stung by reports that FBI scientists had often vastly overstated their level of certainty in matching hair samples and other evidence, issued rules Friday meant to ensure that the experts’ testimony in criminal cases was “supported by sound science.”
The rules, which have yet to be made final, are the latest in a series of steps that the Obama administration has taken to address the problems, including those revealed in a preliminary review last year of FBI testimony in hair-sample cases.
That analysis, which examined 268 criminal cases from 1985 to 1999, found flawed testimony in more than 95 percent of them. More than a dozen of the defendants have been executed or have died in prison.
The guidelines issued Friday provide a framework for FBI testimony involving seven types of forensic evidence, including body fluid, fingerprints and footprints. They seek to inject a more realistic measure of doubt in courtroom testimony.
No longer, for instance, would FBI forensic witnesses be allowed to testify that there was a “zero error rate” in comparing one fingerprint to another or that one sample of blood was a certain match to another.
Instead, they would be required to testify how likely or unlikely a match was found to be, within an “acceptable range of opinions.”
Once the rules are formally adopted, they “will clarify what scientific statements our forensic experts may — and may not — use when testifying in court and…