Automatism defences such as sleepwalking are rare in criminal law cases and expert evidence will always be required to establish whether or not the Defendant was subject to some form of automatism at the time the offence they are charged with was committed.
“I do not doubt that there are genuine cases of automatism, but I do not see how the layman can safely attempt, without the help of some medical or scientific evidence, to distinguish the genuine from the fraudulent” (Hill v Baxter (1958) 1 Q.B. 277, 42 Cr. App. R. 51).
One of the reasons the defence of automatism is so rarely used is that the Courts have traditionally, for the purposes of social protection, interpreted the condition narrowly.
What is automatism?
Automatism is where the Defendant’s acts or omissions lack the rudimentary component of voluntariness, for example, where a person has performed an involuntary movement or action due to “some failure of the mind not due to disease”.
In Bratty v Attorney-General for Northern Ireland  UKHL 3,  AC 386,  3 All ER 523, Lord Denning stated:
‘No act is punishable if it is done involuntarily: and an involuntary act in this context – some people nowadays prefer to speak of it as ‘automatism’-means an act which is 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 he is doing, such as an act done whilst suffering from concussion or whilst sleep-walking. The point was well put by Stephen J. in 1889: ‘Can anyone doubt that a man who, though he might’ be perfectly sane, committed what would otherwise be a crime in a state’ of somnambulism, would be entitled to be acquitted? And why is this?’ Simply because he would not know what he was doing’.
What is the difference between non-insane and insane automatism?
Non-insane automatism means the involuntary act or omission was caused by an external factor. An example of an external factor is a driver being struck by a stone or attacked by a swarm of bees and swerving into traffic (Hill v Baxter  2 W.L.R. 76  1 Q.B. 277). Insane automatism involves the automatism being caused by an internal factor such as epilepsy or, as in the case of R v Hennessy (Andrew Michael)  1 W.L.R. 287 where the Appellant suffered from hyperglycaemia (high blood sugar).
Non-insane automatism is a complete defence and will result in an acquittal. If a person successfully pleads insane automatism, a special verdict of not guilty by reason of insanity would be delivered and the Defendant will normally be committed to a mental health hospital.
Is sleepwalking classed as an automatism defence?
Sleepwalking falls under the defence of automatism. It is most often used as a defence in the case of violent or sexual offences (sometimes referred to as sexsomnia or somnambulism).
In 2009, a man who had strangled his wife during a nightmare walked free from Swansea County Court after a judge directed the jury to bring in a formal not guilty verdict.
The couple were childhood sweethearts and had been married for 40 years. Psychiatrists for the Prosecution and the Defence agreed that the husband suffered from a long-standing sleep disorder, and he had been in a state of automatism when he choked his wife, who he thought was an intruder. The couple’s children told the Court that their father had a history of sleepwalking and during such episodes, he could act strangely. After reviewing the evidence from expert witnesses, the Prosecution stated that sending the husband to a psychiatric hospital would serve no purpose and therefore it was no longer seeking a special verdict of not guilty by reason of insanity.
If the sleepwalking is triggered by alcohol and the Defendant knows that alcohol is likely to precipitate an episode of sleepwalking, then the Defendant would be considered reckless, and a conviction may be the right outcome (depending on the other circumstances of the case).
Automatism defences, especially non-insane Automatism which results in a full acquittal, are especially difficult defences to prove and require witnesses who specialise in neurological and psychiatric disorders to provide expert evidence to assist the Court.
How can Expert Court Reports Ltd help?
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