ABSTRACT
Automatism simpliciter and the insanity defence share several justifications for their status as excuses in criminal law. This chapter discusses some of the wider issues surrounding medicolegal automatism and examines the jurisprudence behind the automatism defence. In particular, the legal and moral principles behind the exemption from criminal responsibility for acts committed during medicolegal automatism need to be examined, and whether or not there are coherent and consistent principles underpinning the law in this area. It is generally required in criminal law that the actus reus and mens rea coincide. The act requirement and the voluntariness requirement, frequently treated as one actus reus requirement, are related but distinct doctrines. A large amount of the confusion surrounding the defence of automatism arises from the conflation between involuntariness and unconsciousness. Yeo makes a useful contrast between involuntariness and unconsciousness, but his analysis includes disinhibition and irresistible impulse as forms of automatism.
