Absent DNA testing, you cannot reliably identify someone’s hair visually. But the FBI testified repeatedly over many years in cases where they asserted a high degree of probability that hair evidence belonged to the defendant. This was scientifically insupportable and it amounted to false testimony that led to many false convictions, including some death penalty cases.

Nearly every criminal case reviewed by the FBI and the Justice Department as part of a massive investigation started in 2012 of problems at the FBI lab has included flawed forensic testimony from the agency, government officials said.

The findings troubled the bureau, and it stopped the review of convictions last August. Case reviews resumed this month at the order of the Justice Department, the officials said.

The FBI freaked out when they realized that virtually every case they were reviewing revealed bad testimony and they sought to change the standards. Fortunately, the DOJ freaked out in response and set things aright again. Still, this should be a much bigger scandal than it is.