How trustworthy are DNA and other crime scene tests?

The criminal justice system has a problem, and its name is forensics. This was the message I heard at the Forensic Science Research Evaluation Workshop held May 26–27 at the AAAS headquarters in Washington, D.C. I spoke about pseudoscience but then listened in dismay at how the many fields in the forensic sciences that I assumed were reliable (DNA, fingerprints, and so on) in fact employ unreliable or untested techniques and show inconsistencies between evaluators of evidence.

The conference was organized in response to a 2009 publication by the National Research Council entitled Strengthening Forensic Science in the United States: A Path Forward, which the U.S. Congress commissioned when it became clear that DNA was the only (barely) reliable forensic science. The report concluded that “the forensic science system, encompassing both research and practice, has serious problems that can only be addressed by a national commitment to overhaul the current structure that supports the forensic science community in this country.” Among the areas determined to be flawed and in need of more research are: accuracy and error rates of forensic analyses, sources of potential bias and human error in interpretation by forensic experts, fingerprints, firearms examination, tool marks, bite marks, impressions (tires, footwear), bloodstain-pattern analysis, handwriting, hair, coatings (for example, paint), chemicals (including drugs), materials (including fibers), fluids, serology, and fire and explosive analysis. (continue reading…)