Title: Evaluating and Explaining the Probative Value of Forensic DNA Evidence

Abstract:

I will explain current technology used for STR-based DNA tests and will discuss a series of factors that may affect the probative value of a DNA match. My primary focus will be factors that create uncertainty about the determination of a "match," including ambiguity in the underlying DNA profiles, problems in assays, incomplete profiles, mixed samples, laboratory error and the potential for "observer effects" (also called examiner bias) in the process of interpretation. For illustration, I will use evidence from actual criminal cases. I will also comment on the difficulty of explaining these issues to lay triers of fact in a courtroom.