The Defence of Intoxication (WA)

By James Stevens, Director and Solicitor, Go To Court Lawyers. Last reviewed 15 April 2026.

The criminal law in Western Australia provides for a defence of intoxication to be used in very limited circumstances. A person who is intoxicated to the point of being unable to understand what they are doing has a defence to a criminal charge only if their intoxication is involuntary. This means that if a person willingly chooses to consume drugs or alcohol and becomes intoxicated, they cannot use their intoxication as a defence.

Legislation

Under the Criminal Code of Western Australia every person is presumed to be and to have been of sound mind until the contrary is proved. Under section 27, a person is not criminally responsible for an act or omission that occurred when they were of unsound mind. The person will not be held responsible if their mental impairment deprived them of the capacity to understand what they were doing, or the capacity to control their actions, or to know that they ought not to do the act or make the omission. This provision applies to someone whose mind is disordered by intoxication or stupefaction where this has occurred without their intent by drugs or intoxicating liquor, or by other means.

Intoxication and intent

Voluntary intoxication is not a defence to a criminal charge. However, it can be factored into an assessment of whether the accused had a particular intention.  This is set out in Section 28(3) of the Criminal Code, which provides:

“When an intention to cause a specific result is an element of an offence, intoxication whether complete or partial, and whether intentional or unintentional, may be regarded for the purpose of ascertaining whether such an intention in fact existed.”

The defence of intoxication is restricted to those offences of which an ‘intention to cause a specific result’ is an element. An example of such an offence is the crime of murder under section 279 of the Criminal Code, which provides:

“if a person unlawfully kills another and:

1. The person intends to cause the death of the person killed or another person; or
2. The person intends to cause a bodily injury of such a nature as to endanger, or be likely to endanger, the life of the person killed or another person; or
3. The death is caused by means of an act done in the prosecution of an unlawful purpose, which act is of such a nature as to be likely to endanger human life

the person is guilty of murder.”

In the 1978 High Court of Australia decision of Viro v The Queen, Justice Gibbs set out how a judge must direct a jury when intoxication is an issue. His Honour stated:

“In a case where there is evidence fit to be considered by a jury that the accused was intoxicated as a result of the consumption of drink or drugs, it is not enough to tell the jury that the Crown must prove beyond reasonable doubt that the accused had in fact formed the requisite special intent. They should also be told that the fact that the accused was intoxicated, whether by drink or drugs or by a combination of both, may be regarded for the purpose of ascertaining whether the special intent in fact existed.”

Burden of proof

The evidentiary burden rests with the accused to raise the issue of intoxication. If an accused seeks to defend a charge on account of unsoundness of mind, they must prove that on the balance of the probabilities they are not criminally responsible for their actions. For the defence to succeed, the intoxicating substance must be found to have had an overpowering effect on the accused's mind at the time of the commission of the relevant acts.

It is a question of fact whether the accused was intoxicated.

If the accused is unable to establish a defence of intoxication, generally the presence of an intoxicating substance in their system will suggest that there has been no more than a chance of mood that caused the accused to engage in a course of behaviour that they may not have done if they had been sober.

Plea in mitigation

If an accused is unable to establish a defence of intoxication and enters a plea of guilty to an offence, intoxication may be raised during sentencing. There are no clear common law principles regarding whether intoxication should be considered an aggravating or mitigating factor at sentencing.

While some states within Australia have specifically abolished intoxication as a mitigating factor, Western Australia has not. The relevance of intoxication and substance abuse as a whole is largely dependent upon the circumstances of the offence.

If substance abuse is considered a cause of regular offending, the court is likely to consider this an aggravating factor. This is particularly the case if the accused has not sought any treatment for their substance abuse in the process of sentencing.

If you have been charged for an offence to which you believe the defence of intoxication may apply or wish to know how intoxication may affect your matter, it is important to seek legal advice.

If you require legal advice in any legal matter, please contact Go To Court Lawyers.