The defence of intoxication in Western Australia is governed by section 28 of the Criminal Code Act Compilation Act 1913 (WA), read together with section 27, which deals with the defence of insanity. The two provisions operate together and the distinction between them is critical to understanding when intoxication can actually be used as a defence — and when it cannot.
The Key Distinction: Voluntary vs Involuntary Intoxication
Western Australian law draws a hard line between intoxication that was intentional and intoxication that was not.
Involuntary intoxication — where a person’s mind was disordered by drugs, alcohol, or other substances without any intention on their part, such as being unknowingly drugged — may give rise to the defence of insanity under section 27. Under that section, a person is not criminally responsible for an act or omission if, at the time of the offence, they were in such a state of mental impairment that they lacked the capacity to understand what they were doing, to control their actions, or to know that they ought not to do the act. If involuntary intoxication produced that level of impairment, a full acquittal is available.
Voluntary intoxication — where a person intentionally consumed alcohol or drugs, whether or not they intended to use it as an excuse for criminal conduct — is not a defence in Western Australia. A person who chose to become intoxicated remains criminally responsible for their actions under section 28(2), regardless of how severely their judgment or self-control was affected.
Where Voluntary Intoxication Can Still Be Relevant
Although voluntary intoxication is not a defence, it is not entirely irrelevant under WA law. Section 28(3) provides that intoxication — whether voluntary or involuntary, and whether complete or partial — may be taken into account when the court is determining whether an accused had the intention required for a specific intent offence.
Specific intent offences are those where the prosecution must prove the accused intended a particular result, not merely that they did the act. Examples include murder, assault with intent to cause grievous bodily harm, and robbery with intent to commit an indictable offence. In these cases, severe intoxication may raise a genuine doubt about whether the accused was capable of forming the requisite intent — which can affect the outcome even where intoxication does not provide a complete defence.
This is a significant but limited concession. It does not mean intoxication excuses liability for specific intent offences — it means it is a factor the court may weigh when assessing whether the prosecution has proven the required mental element beyond reasonable doubt.
The Burden of Proof
The defence of intoxication under section 28 is notoriously difficult to establish. The burden rests with the accused to demonstrate, on the balance of probabilities, that they were deprived of the relevant mental capacity at the time of the offence. This is a higher bar than simply showing the person was drunk or affected by drugs. Courts have been clear that the impairment must have been of a degree that genuinely deprived the accused of the capacity described in section 27 — not merely that it affected their judgment or inhibitions.
Voluntary contribution to an impaired mental state — for example, consuming cannabis that then triggered a psychotic episode — has been held by the Supreme Court of Western Australia not to satisfy the defence, even where genuine mental impairment resulted. The accused’s role in causing the intoxication remains a relevant consideration.
What This Means if You Are Facing Charges
If intoxication was a factor in the circumstances of your alleged offence, whether voluntary or involuntary, the legal implications depend heavily on the specific charge, the degree of impairment, how it came about, and what the prosecution must prove. These are not straightforward questions and the law in this area requires careful analysis of the facts.
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