Must reading for anyone interested in the criminal justice system (which should, of course, be everyone):the report on Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods from the President’s Council of Advisors on Science and Technology. The report looked at pattern matching forensic disciplines such as bite mark matching, shoe print matching, blood spatter analysis, fingerprint matching and hair fiber analysis. It also looked at DNA testing when investigators find biological material from multiple sources. With the exception of single-source DNA testing, the report found serious deficiencies in all areas of forensics it studied.
As the Washington Post points out in analyzing the report, it is DNA testing that has exposed these other flaws in forensic science, by proving innocence in cases where other forensic “sciences” had argued for guilt. But DNA testing isn’t a panacea; the percentage of all cases in which DNA testing can conclusively prove or disprove guilt is 10 percent at most. The flaws in the system that DNA exposed in those 10 percent of cases logically must persist throughout the system, and likely at about the same rates. If we don’t correct the problems with other forensic disciplines that DNA testing has exposed in those 10 percent of cases, and that the report explores in depth, those problems will continue in the remaining 90 percent of cases.