ABSTRACT
This chapter is concerned primarily with the legal rules on expert evidence, but also deals with some particular issues with medical science. Expert evidence is central to the defences of automatism and insanity, as these issues are nearly always outside the jury's expertise. Where the behaviour is complex, issues arise about whether or not it is compatible with medicolegal automatism, regardless of what mental state the accused was in at the time. Some sleep experts believe that more complex behaviour occurs during a confusional arousal at the end of a sleepwalking episode, but confusional arousals are short-lived. Prominent North American sleep experts believe that there is no good evidence that alcohol triggers forensic sleepwalking episodes at all. Evidence-based medicine is not a requirement of the criminal courts, and the application of its principles is particularly problematic in the case of forensic sleep disorders, because there is a dearth of good quality research.
