Automatism is an act done by a person who is not conscious of what s/he is doing. It can be an act done by the muscles without any control by the mind, such as a spasm, a reflex action or a convulsion; or an act done by a person who is not conscious of what s/he is doing, such as an act done whilst suffering from concussion or while sleep-walking. Absence of volition in respect of the act involved is always a defense to a crime. The defense of automatism also bears on the voluntariness of a defendant's actions. When the automatistic condition arises from a disease of the mind that has rendered the accused insane, then the accused is not entitled to a full acquittal, but to a verdict of insanity. The condition in that instance is referred to as insane automatism.
The following is an example of a caselaw on Automatism:
Automatism has been defined as the existence in any person of behavior of which he is unaware and over which he has no conscious control. Automatism is behavior performed in a state of mental unconsciousness apparently occurring without will, purpose, or reasoned intention. Automatism connotes the state of a person who, though capable of action, is not conscious of what he is doing. Automatism manifests itself in a range of conduct, including somnambulism (sleepwalking), hypnotic states, fugues, metabolic disorders, and epilepsy and other convulsions or reflexes. [Schlatter v. State, 891 N.E.2d 1139 (Ind. Ct. App. 2008)]