Insanity, Automatism and Intoxication Lecture - Hands on Example

The following scenario will assess your knowledge of the defences covered here and give you a chance to have a go at applying them in relation to offences committed in a practical context. These aren’t like other areas of the law where you establish the actus reus and mens rea so it may take a bit of adjusting before you feel really confident.

Read over the following passage and pull out any material facts as you go. Once you have done this try and identify what defences may be relevant and have a go at applying them using the case law we have looked at together.

If you’re feeling a little daunted by the question don’t worry! Defences can take time to get your head around and the you’re taking all the right steps just by having a look at practice questions and familiarising yourself with them. A step by step outline answer has been provided for you that contains the points you should discuss when you go about addressing the scenario. Use this as guidance in putting together or checking your own answer. There is nothing raised in this question that we haven’t already covered so refer back to the notes to help you out. You’ll find that you have everything you need to do a really good job!

John is sleeping over his Cousin Zoe’s house before a big family wedding the next day. Zoe is really into aromatherapy and has lots of oil diffusers around the house. In John’s room Zoe puts an oil designed to aid sleep into a diffuser and it sends John to sleep really quickly. A couple of hours into the night however the scent of the oil triggers a strange reaction in John’s brain. He gets up, still asleep and walks into Zoe’s room. Zoe wakes up see’s John standing there and asks him what he is doing. John lashes out and pushes her away. The force of hitting here wakes John up and he is shocked and confused by his behaviour.

The next day at the wedding, Zoe’s boyfriend Phillip see’s her broken nose and black eye and learns what happened the night before. He is furious with John and wants to confront him and give him a broken nose and a bruised face of his own to make up for what has happened to his girlfriend. Phillip is not the tallest of men and John is over 6”4. Phillip is a little intimidated by this so decides to have a large whiskey before he confronts John in order to calm his nerves and make him seem more confident. It is an open bar and the whiskey is a particularly good blend. Phillip enjoys his drink so much he has another, and another, until he has drunk most of the bottle. He stumbles away from the bar into John and smacks him hard, breaking his nose and cutting his eye. Phillip is so drunk at this point he has little control over what he is doing and a is not actually even really aware of who John is.

Discuss any defences that John may have in relation to the GBH on Zoe and any defences Phillip may have in relation to the GBH caused to John.


  • Possible defence of automatism. Whether it will be insane or non-insane automatism will depend on whether the cause is internal or external. It will be preferable to show the cause is external where possible to avoid the special verdict and achieve a complete acquittal.
  • Burgess states that sleepwalking is an internal cause, however following R v T where possible it may be possible to argue that internal cause was trigged by an external factor. In this case, strong case that the oil triggered the chemical reaction of sleepwalking and thus is more properly aligned to Quick where the automatism was caused by the application of an external substance to the body.
  • Uncertain which way the court would proceed so consider both defences.

Insane Automatism

  • M’Naghten rules.
  • Defect of reason arising from a disease of the mind so that D did not appreciate the nature and quality of his acts or know what he was doing was wrong.
  • Applying Clarke, defect of reason was more than mere absent mindedness
  • Burgess confirms that sleep walking is a disease of the mind.
  • Applying Codere, the defendant clearly did not know the nature and quality of his acts as he was not conscious of what was happening.
  • On the facts therefore the M’Naghten rules are all satisfied and the defence of insane automatism will be available to John. The starting point is that all defendants are presumed sane so the burden is on John to establish on the balance of probabilities. If successful it will result in a special verdict of not guilty by way of insanity.

Non-Insane Automatism

  • Bratty definition. Something was done by the defendant's muscles without the control of his mind or an act done by a person who is not conscious of what he is doing. Need to show: (i)Total loss of voluntary control as per Broome v Perkins (ii) external factor as per Quick.
  • Clear from the facts that John was not conscious of what he was doing at the time and he had suffered from a total loss of voluntary control as he was asleep. If it can be argued in line with Quick, that the external factor of the oil caused the reaction then this will be sufficient.
  • Specific/basic distinction is irrelevant here as John was not reckless in becoming an automaton and therefore will likely be acquitted.



  • Voluntary intoxication by alcohol or dangerous substance is no defence as per Hardie.
  • s.18 GBH is a crime of specific intent so if the defendant was so drunk he was prevented from forming mens rea the charge will be the basic intent alternative, in this case s.20 GBH.
  • However, a caveat applies in cases of Dutch courage such as this following the ruling in Gallagher and the defendant will be charged as if he held the mens rea at the relevant time.
  • Intoxication will therefore provide no defence to Phillip and will actually act to increase his liability to a specific intent crime when at the time of committing the offence he did not hold the requisite mens rea.

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