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Intoxication (WA)

In Western Australia, the criminal law provides a defence of intoxication that can be relied on only under very limited circumstances. An accused person who was so intoxicated that they were unable to understand what they were doing can rely on this as a defence only if their intoxication was involuntary. This means that if a person freely chooses to take drugs or alcohol and becomes intoxicated, they cannot use intoxication as a defence. This page deals with the defence of intoxication in WA.


Under the WA Criminal Code, everyone is presumed to be of sound mind unless proven otherwise. Under section 27, an accused is not criminally responsible for acts or omissions that occurred when they were of unsound mind. 

A person can rely on the defence of mental impairment if their mental condition meant that they were unable to understand what they were doing, could not control their actions, or could not know that they ought not to do the act or omission. 

This provision applies to a person whose mind is disordered by intoxication only if they became intoxicated without intending to do so (also known as involuntary intoxication).

Intoxication and intent

Voluntary intoxication is not a defence in Western AustraliaHowever, an accused person’s voluntary intoxication can be taken into account when assessing whether they had a particular intention. This is made clear 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.”

This provision applies only to offences that involve an intention to bring about a specific result. An example of such an offence is murder under section 279 of the Criminal Code. Section 279 states:

“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.”

The 1978 High Court of Australia decision of Viro v The Queen, contains an explanation of how a jury must be directed in a case where intoxication is an issue. Justice Gibbs 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 accused bears the burden of proof when raising the issue of intoxication. If an accused person seeks to defend a charge based on unsoundness of mind resulting from involuntary intoxication, they must establish that on the balance of the probabilities they were of unsound mind and therefore are not criminally responsible. For the defence to succeed, the intoxicating substance must have had an overpowering effect on their mind at the time of the relevant acts.

It is a question of fact whether an accused was intoxicated and whether their intoxication was voluntary.

Plea in mitigation

If an accused cannot establish a defence and pleads guilty or is found guilty of an offence, intoxication may be raised during sentencing. However, there are no clear common law principles about whether intoxication should be regarded as an aggravating or mitigating factor at sentencing.

While some states have specifically abolished intoxication as a mitigating factor, WA has not. The relevance of intoxication and substance abuse as a whole depends on the circumstances of the offence. 

If substance abuse is a cause of regular offending by the accused, the court is likely to consider it to be an aggravating factor, particularly if the accused has not sought any help with their substance abuse issues.

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

Fernanda Dahlstrom

This article was written by Fernanda Dahlstrom

Fernanda Dahlstrom has a Bachelor of Laws, a Bachelor of Arts and a Graduate Diploma in Legal Practice. She has also completed a Master’s in Writing and Literature. Fernanda practised law for eight years, working in criminal defence, child protection and domestic violence law in the Northern Territory and in family law in Queensland.

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