In the United Kingdom and the United States and those jurisdictions based on UK law, for a person to be convicted of a crime, the law requires that the defendant has committed a criminal act (actus reus) and that he had a knowing intent to commit that act (mens rea). It is this element that must be shown to be lacking when a defense of automatism is used.1-4
The legal definition of automatism is based on the doctrine of mens rea, the fundamental basis of English law. Everyone who has reached the age of discretion is, unless the contrary is proved, presumed by law to be sane and accountable for his actions. Actus non fecit reus mens sit rea means the deed does not make a man guilty unless his mind is guilty. Unless the offense is a statutory one that carries an absolute liability (e.g., driving with a raised blood alcohol level), the doctrine of mens rea, or the presence of a guilty mind, can only be negated by certain considerations.