SANE AUTOMATISM the defence at law


This month we highlight the often-misunderstood defence in criminal law of SANE AUTOMATISM

In our criminal law jurisdiction, all criminal offences require proof that an accused person’s actions were voluntary.

Failure to prove the accused acted voluntary results is an acquittal (not guilty).

The term Sane Automatism is used to describe a situation whereby the accused acted without been in control of his/her action, in other words their conduct was not voluntary.

The aim is to avoid a mental illness special verdict. Insane Automatism which results in a person found not guilty due to insanity and ordered to be held in a mental health facility. 

So rather the defence of Sane Automatism explains the actions of an accused person as only a ‘transient malfunction’ of an otherwise sound mind, allowing for a not-guilty acquittal verdict.

The accused person bears an evidentiary burden in relation to the defence of Sane Automatism – meaning the accused person must provide some evidential basis for the defence, and then the burden shifts to the prosecution to prove beyond a reasonable doubt that the defence does not apply (ie: negate the defence).

A range of conditions may give rise to a state of Sane Automatism which may serve to negative voluntariness and provide an evidentiary basis for an accused person.

Some examples include: -

  • Extreme states of intoxication caused by alcohol (O’Connor & Martin);
  • Drugs (Haywood) (however NOT in relation to intoxication and/or physical element of the act);
  • Concussion (Wogandt);
  • Sleepwalking (Jiminez);
  • Hypoglycaemia (Quick);  
  • A sudden illness (Hill v Baxter); 
  • A stoke/heart attack, or being attacked by a swarm of bees;
  • Dissociation caused by a severe psychological blow (Falconer);
  • Post-traumatic stress disorder  

The most common case examples are discussed below: -


Dissociation can be used as an external factor for the defence of Sane Automatism. It was successfully raised as a foundation for Sane Automatism in Donyadideh (unreported) and related to the accused horrifying torture treatment in Iran.


In Quick & Paddison [1973] an English case, the Court of Appeal allowed the defence of Sane Automatism when the accused injected himself with insulin, then drunk a substantial amount of alcohol without consuming any food. The result had the consequence of the accused suffering then from very low blood sugar (Hypoglycaemia). The Court held the malfunction of his mind was not due to the internal forces of diabetes, but instead the external forces of the injection of insulin, coupled with alcohol and lack of food. Hence, the accused was entitled to rely on the defence of Sane Automatism/

In contrast the case of Hennessy (1989) the accused who also was a diabetic and sought to rely on the low blood sugar. However, the Court rejected it in this case because unlike an external event here the accused had failed to take his insulin. The result had the consequence of suffering from hyperglycaemia not Hypoglycaemia.  The health condition was an internal event, and the defence of Sane Automatism was not available because no external factors had existed at the time of the offence, other than his internal pre-existing diabetic condition.


In Parks (1992) the accused was acquitted on the defence of Sane Automatism because he it was held that he was sleepwalking at the time of he committed the offence. In this case, sleeping walking was characterized as a sleep disorder external to the mind and not a neurological disorder internal to the mind.


In Wogandt (1983) the accused bashed a referee this occurred soon after a heavy tackle during the football match. The Appeal Court quashed the conviction and ordered a new trial with Sane Automatism to be left to the jury.

If you or someone you know is facing criminal charges. Contact us at Rep-Revive Criminal & Employment Lawyers for initial free consultation on 9198 1996 or visit our website at for more defences at law.



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