The importance of scientific evaluation of biological evidence — Data from eight years of case review

Abstract

In 2009, the National Research Council published a report stating that the addition of more science and technology into the field of forensic science in the United States would be of great benefit to the judicial system. As a starting point to address this NRC report, one needs to make an assessment of the system. One factor that is continuously requested is an estimate of an error rate. In any given scientific area of forensics that is difficult to quantitate except by external review and audits. After eight years of requested defense review of cases with biological and DNA evidence, most cases appear to be scientifically sound in test methods and procedures. However, there were some cases where errors in the forensic science process did occur. This article takes information compiled from those eight years of defense review and summarizes the cases where errors have been discovered and discusses the scientific implications of these errors. The scope of this article is limited to crime scene collection and forensic science laboratory testing of biological materials for body fluid identification and DNA individualization to a source. The greatest value of defense review comes from (a) providing effective balance and independent oversight to the judicial process and (b) collecting data into a format that can be useful as a guide in training programs.