The science of proof: forensic science evidence in English criminal trials

Abstract

Previous chapters of this Handbook have indicated the rapidly expanding contribution of forensic science to criminal investigations across a broad range of factual scenarios and types of criminality, employing an increasingly sophisticated array of scientific technologies and forensic techniques. This chapter takes as its central focus the criminal trial in England and Wales, in order to explore the translation of forensic science into admissible evidence capable of contributing to the conviction of the guilty and exoneration of the innocent. The courtroom is the crucible in which science and law confront each other most directly in the administration of justice, an interface typically mediated through the testimony of one or more expert witnesses. A central task for this chapter is accordingly to identify, explain and critically evaluate the legal rules of evidence and procedure which regulate the admissibility, presentation and interpretation of expert witness testimony in criminal trials. The impact of forensic science evidence on the course and outcome of criminal proceedings is often significant and sometimes dispositive. Yet forensic science evidence has also attracted its fair share of controversy in recent decades – on some occasions receiving plaudits for its impressive contributions to controlling crime and visiting offenders with their just deserts, at other times berated as a potent cause of miscarriages of justice.