God's signature: DNA profiling, the new gold standard in forensic science

In the mid-1980s, when the first DNA profiling techniques were developed, the name DNA 'fingerprinting' was widely used. At the time, fingerprinting was a well-established forensic method, and it was rarely questioned in the courts. Fingerprint examiners were permitted to describe matching prints as evidence of individual identity, and they were not required to give probability estimates. Despite its nominal association with the older technique, DNA 'fingerprinting' went through a period of controversy, especially in the US courts. The association with fingerprinting was questioned, and experts were required to qualify their testimony with probability figures. Heated debate occurred in scientific publications and law courts about the statistical and population genetic assumptions that went into the probability calculations presented in court cases. However, by the late 1990s DNA profiling was so widely accepted that it became a basis for invidious comparison with all other forms of forensic evidence, including fingerprinting. In the past three years, the admissibility of fingerprint evidence has been challenged in several US federal and state courts. This article discusses the socio-legal and socio-technical issues that led to the inversion of credibility that characterized the intertwined history of the two techniques.