In the 20 or so years prior to 2000, forensic analysis of hair was used against defendants in about 2,500 US trials. Reviews of 342 of these cases by the US Justice Department and the FBI revealed that in 257 of 268 of these cases, 26 of 28 FBI examiners gave flawed testimony, overstating matches of the hair. Analysis of hair, which has been conducted microscopically, along with other pattern-based analyses, has been used as evidence in more than 25% of 329 cases since 1989 in which defendants were exonerated based on DNA analysis. During the time under review, the FBI hair examiners taught 500–1,000 state and local forensics personnel how to testify. Until 2012, the FBI did not have written standards for producing scientifically accurate testimony in court based on hair analysis. The FBI plans to complete standards for 19 other forensics disciplines this year.

Source: The Washington Post