‘Sleep, Sex and Violence’?

19 September 2023

Allison Summers KC

It is over 17 years since I first ran a defence based on parasomnias. The circumstances of the offence were that in the early hours a 28-year-old man, whilst staying over at a friend’s house, had left the living room where he was sleeping, walked down the short hallway to his friend’s 15-year-old stepdaughter’s room and got into bed with her (he had slept in her room the night before) and touched her on her breasts. Two experts later (a sleep disorder expert and a neurologist) and I had evidence supportive of his case that what he had done had been in a state of sleep. I ran a defence of non-insane automatism based on somnambulism (sleepwalking) and sexsomnia (sexual activity in sleep). The jury acquitted. 6 years later I represented the same man charged with attempted murder. He had left his house, walked the short distance to his friend’s house, entered by an unlocked side door, went into her bedroom, got on her top of her and then put an axe to her head. Same experts, same defence, save that in this case the judge determined the appropriate defence was insanity and not non-insane automatism. The jury rejected insanity and the defendant was convicted.

This area of law was described in 1973 as a ‘quagmire’[1] and frankly not much has changed in almost 50 years.

Where the defence of automatism is raised by a defendant, two questions fall to be decided by the judge before the defence can be left to the jury. The first question is whether a proper evidential foundation for the defence has been laid. This will usually come from an expert in sleep disorders but may come from witnesses. The second question is whether the evidence shows the case to be one of insane automatism (often referred to as insanity) or one of non-insane (sane) automatism.

In broad terms, non-insane automatism is available where a defendant has performed an act but has done so involuntarily and that the cause of this was an external event. Insane automatism or insanity require the defendant to have suffered from a disease of the mind giving rise to a defect of reason which renders him not responsible in law for his actions (often referred to as ‘internal factors’). It is important to appreciate that ‘legal insanity’ is different from insanity used in a psychiatric or other medical context.

A successful defence of non-insane automatism will result in an acquittal. A successful defence of insanity leads to a special verdict of ‘guilty by reason of insanity.’ Where such a verdict is returned, the court has only three disposals available: Hospital Order; a Supervision Order (requiring a defendant to be under the supervision of a social worker or more likely, under an officer of a local probation board for up to two years) or an Absolute Discharge.

The two defences bring different burdens. If the defence is non-insane automatism, the prosecution bears the legal burden of proving, beyond reasonable doubt, all the elements in the offence. This would mean the prosecution proving, beyond reasonable doubt, that there was a voluntary act. If the defence is insanity, the burden of proof rests on the defence to prove its case on a balance of probabilities.

The broad internal/external distinction is troublesome and has led to difficulties when the issue of automatism is raised. The case law has found acts committed because of head-injury (concussion), anaesthetic and sneezing to give rise to a defence of non-insane (sane) automatism. Conditions such as epilepsy, hyperglycaemia, hypoglycaemia, and sleepwalking have been found to give rise to insane automatism (insanity). Indeed, it is often said that the case of R v Burgess (1991) made it clear that sleep walking is not a form of (non-insane) automatism but a form of insane automatism (insanity).

There have however been other cases where the defence of (non-insane) automatism was left to the jury rather than insanity, resulting in complete acquittals. Indeed, in a case I did in 2021 this is exactly what happened. The defendant was charged with raping his partner as she lay in bed next to him other in the early hours of the morning. The sleep expert was of the view that the primary precipitating factor was most likely to have been the fact that the complainant and defendant who had had sex earlier in the evening had fallen asleep naked in a spooning position. It was said this external stimuli was the most likely trigger for the sexual act in sleep rather than an internal, organic issue and as such the judge left non-insane automatism to the jury. The defendant was acquitted. It should therefore not be assumed that all cases involving parasomnias will only give rise to a defence of insanity rather than non-insane automatism. So long as we have this rather crude distinction between external and internal factors, experts need to be pressed as to what the trigger is likely to have been.

In my first case, the judge didn’t even ask for submissions, he simply determined that if the defendant was asleep, he deserved to be acquitted. The second case was more difficult because in the intervening period, a former partner had provided information to the sleep experts that they had experienced violent sexual acts when the defendant appeared to be asleep particularly at times when the defendant was under stress, leading the experts to conclude that in the absence of an obvious external trigger, there was more likely to be an internal organic issue although none of them were able to identify this as a medical fact. I have no doubt the overwhelming concern for the judge was that if the defence was true, then this man was dangerous, and he should therefore not have the opportunity of a complete acquittal. Having regard to the disposals available he must have inevitably thought something is better than nothing. But even if such an approach may be understandable it is still disingenuous and wrong. 

The reality is that in many cases of parasomnias the distinction between internal and external factors is neither legally nor scientifically sound and until the law addresses this the decisions of judges will continue to have something of the arbitrary about them.

Allison Summers KC appeared in the 2022 BBC documentary Sexsomnia: Case Closed? which looked at some of the legal issues relating to prosecuting and defending cases when sexsomnia was raised.

[1] R v Quick [1973]

19 September 2023


Allison Summers KC

Call 2000     Silk 2020

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