There's been some doubt as to the accuracy of some forensic science approaches, but Scientific American's Steve Mirsky reports that a judge speaking at a recent meeting says that they are still being used because they are "better than nothing."
A 2009 report from the National Academy of Sciences found that a number of forensic techniques — such as blood-spatter, handwriting, and hair analysis — aren't supported by rigorous evidence. DNA analysis was the only approach spared the brunt of the report's criticism, the New York Times noted at the time. The report found that that the analyses were conducted "poorly trained technicians who then exaggerate the accuracy of their methods in court."
That's borne out by what Mirsky reports that Jed Rakoff, United States District Judge for the Southern District of New York, said at the American Association for the Advancement of Science meeting last month. Rakoff recalled a case in which he asked a tool-mark expert about his error rate and the error rate of the approach he used and the expert said it was zero. "And I said how can it be zero? And he said well, in every case I've testified, the guy's been convicted," he said.
Despite misgivings regarding these approaches, Rakoff said he thinks courts still allow them to be introduced as evidence because they have a level of objectivity and are useful. "The problem of course is it comes heralded as science, and that gives it a weight that is probably disproportionate," he added.