Legal versus non-legal approaches to forensic science evidence

Abstract

In their attempts to determine the admissibility and probative value of forensic science and medicine evidence, common law courts have tended to focus on considerations such as: the formal qualifications and training of the analyst, the analyst’s experience doing the same or similar things, the existence of a field, whether the evidence might assist the jury, apparent partisanship and plausibility, the overall strength of the case and even the perceived need to accommodate technological innovation. This article reviews conventional English approaches to the admission and evaluation of expert evidence. It aims to contrast legal approaches to forensic science evidence with the kinds of criteria being promoted by a range of peak scientific organisations. This comparative exercise suggests that admissibility jurisprudence and legal practice might be misguided, particularly in their attempts to regulate the comparison or pattern matching disciplines. The article will suggest that courts have privileged the wrong kinds of heuristics in their attempts to engage with scientific and technical forms of knowledge. More disturbingly, it questions whether conventional admissibility standards, even in conjunction with trial safeguards, provide jurors and judges with the kinds of information required to rationally assess much of the incriminating expert opinion evidence routinely presented in criminal proceedings.