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Man who committed sexual assault whilst sleepwalking is found not guilty by reason of insanity

After a night of drinking with friends in August 2019, Dale Kelly slept in the spare room of his friend’s house.  Kelly’s friend was sleeping with his girlfriend, the victim, in the next room, when Kelly wandered in during the night and allegedly touched her intimately.  Apparently waking up confused as to why he was in his friend’s bed, Kelly left the house and was subsequently arrested.

At trial, Kelly told the court that he was dreaming of having sexual intercourse with his girlfriend. Kelly suffers with parasomnia, a sleep disorder, and has a history of sleepwalking.  Kelly successfully raised the defence of insanity on the basis that he committed the assault whilst suffering from pararomnia.  The special verdict of ‘not guilty by reason of insanity’ was returned by the jury.

The standard of proof in insanity cases

Normally, the burden of proof is placed upon the Prosecution to prove that a Defendant is guilty, which must be proven ‘beyond all reasonable doubt’. However, when a Defendant raises the defence of insanity, this burden of proof is reversed and the onus is on the Defendant to prove they have a successful defence. This burden of proof is a lower threshold to surmount, and requires the Defendant to prove that they are not guilty on ‘a balance of probabilities.’

The law of insanity

To successfully raise the defence of insanity, one must prove the following elements as established by the House of Lords in the historic case of M’Naghten [1943] UKHL J16:

  1. The Defendant was insane at the time of committing the offence. This includes temporary bouts of insanity, such as sleepwalking;
  2. The Defendant was suffering from a defect of reason;
  3. This defect of reason arises from a disease of the mind. Disease of the mind encompasses any disease which internally affects one’s mental faculties, impacting their memory, understanding and reason. It is not the case that external factors can cause one to suffer from a disease of the mind, such as intoxication;
  4. The Defendant 1) must not know what he was doing, or 2) must not know that what he did was wrong. If the Defendant relies on the former, the Defendant must show that he did not know or understand the physical nature and quality of the act. If the Defendant relies on the latter, it must be proven that he did not know that the act was contrary to the law. Kelly relied on the former, and claimed that he did not know what he was doing because he was asleep.


In the case of R v  Burgess [1991] 1 QB 92, the Court of Appeal held that sleepwalking constituted ‘insanity.’ In Kelly’s case, the court held that parasomnia was an internal disease of the mind, and was not caused by any external factors. Kelly did undergo tests which confirmed he suffered with episodes of parasomnia.


An individual found not guilty by reason of insanity still stands to be sentenced; however the options open to the sentencing judge are limited.  By virtue of the Criminal Procedure (Insanity) Act 1964, the Court has the power to make either; 1) a Hospital Order (which lasts initially for 6 months), 2) a Supervision Order or 3) an absolute discharge (the Defendant is released). Kelly’s sentencing hearing is yet to take place.


If  you are being investigated or prosecuted for a sexual offence, click here to see how Brett Wilson LLP's experienced team of criminal defence solicitors can assist you.


Legal Disclaimer

Articles are intended as an introduction to the topic and do not constitute legal advice.