Forensic science evidence and the limits of cross-examination

The ability to confront witnesses through cross-examination is conventionally understood as the most powerful means of testing evidence, and one of the most important features of the adversarial trial. Popularly feted, cross-examination was immortalised in John Henry Wigmore’s (1863–1943) famous dictum that it is ‘the greatest legal engine ever invented for the discovery of truth’. Through a detailed review of the cross-examination of a forensic scientist, in the first scientifically-informed challenge to latent fingerprint
evidence in Australia, this article offers a more modest assessment of its value. Drawing upon mainstream scientific research and advice, and contrasting scientific knowledge with answers obtained through cross-examination of a latent fingerprint examiner, it illuminates a range of serious and apparently unrecognised limitations with our current procedural arrangements. The article explains the limits of cross-examination and the difficulties trial and appellate judges — and by extension juries — experience when engaging with forensic science evidence.