Automatism is an unusual defence. It refers to situations where you acted involuntarily or unintentionally because of some other factor at play – for example, where you assault someone while you are sleepwalking or having an epileptic fit, or where you experience significant trauma and you ‘black out’ so that you have no recollection of the incident.

For automatism to be made out, you must prove to the court on the balance of probabilities that:

1. Some ‘external factor’ caused you to act that way you did

You must show that there was some ‘external factor’ that was the sole cause of your actions.

Examples of ‘external factors’ include where you have suffered an adverse reaction to prescribed medication, where you were sleepwalking, where you were having an epileptic fit, or where you suffered a ‘dissociative state’ following significant trauma – in other words, where you ‘blacked out’ with no recollection of what had happened.

You will not be able to argue automatism where your actions were self-induced – for example, where you deliberately took more than the prescribed amount of medication and suffered a bad reaction.

It is important to note that automatism will not be made out where an underlying mental illness caused your actions. In these cases, you may be found not guilty on the basis of mental illness – see below.

2. Your actions were involuntary and unintentional

You must show that your actions were involuntary and unintentional; that is, your actions were unwilled and uncontrollable, for example, where you experience a spasm, reflex or a fit.

3. That you were not suffering from a mental illness at the time of the offence

If you argue automatism, it is important to establish that you were not suffering from a mental illness which caused your actions. This is because if you are found ‘not guilty on the basis of mental illness,’ the court may order that you spend time in a psychiatric hospital.

Generally, courts will accept an argument of automatism where an ordinary person would have ‘cracked under the pressure’ in the same way as you did, and it is unlikely that the episode will recur.

You will be able to present medical evidence of your condition in court to support your argument of automatism.

If you raise the defence of automatism, the prosecution will then have to prove beyond a reasonable doubt that you were not suffering from automatism, or that you were instead suffering from a mental illness at the time of the offence.

If your defence is accepted in court, you will be found ‘not guilty.’