Why DNA Likelihood Ratios Should Account for Error (Even When a National Research Council Report Says They Should Not)

The possibility of error limits the strength of DNA evidence in the same way that it limits the strength of other kinds of legal evidence. However, a 1996 report by the National Research Council recommends against estimating an error rate derived from proficiency tests to help identify the probative value of DNA evidence. The Committee's arguments are identified and critiqued. It is argued that error rate data derived from broad reference classes such as "all DNA laboratories" provide a relevant starting point for estimating the risk of error in individual cases. Likelihood ratios that fail to incorporate this estimate may be misleading