The defence of mistake of fact is an essential legal safeguard under Section 24 of the Criminal Code Act Compilation Act 1913 (WA).
It provides individuals facing criminal charges with a potential avenue for defence where they acted under an honest and reasonable but mistaken belief about the facts of a situation.
If proven, this defence can limit criminal responsibility to the extent that the mistaken belief would make the actions lawful, as outlined in Section 24 of the Criminal Code Act Compilation Act 1913 (WA).
Here, we explain how the defence works, where it applies, and the legal principles involved.
What is the Defence of Mistake of Fact?
Section 24 of the Criminal Code Act Compilation Act 1913 (WA) provides:
“A person who does or omits to do an act under an honest and reasonable, but mistaken, belief in the existence of any state of things is not criminally responsible for the act or omission to any greater extent than if the real state of things had been such as the person believed to exist.”
This means that a person cannot be held criminally responsible for their actions if:
- They genuinely believed in a certain set of facts;
- Their belief was reasonable given the circumstances; and
- If the facts as they believed them to be were true, their actions would not have been unlawful.
This principle ensures that individuals are judged based on their actual mental state at the time of the alleged offence, rather than on the actual facts that came to light later.
Elements of Mistake of Fact
To successfully raise the defence of mistake of fact, the following elements must be established:
- Honest Belief: The accused must genuinely believe in the mistaken fact at the time of the alleged offence. This belief must be sincere and not fabricated.
- Reasonable Belief: The belief must be reasonable when viewed through the lens of an ordinary person in the same circumstances. The court will evaluate all surrounding factors, such as the accused’s knowledge, experience, and the situation they were in.
- Factual Basis: The mistaken belief must concern a factual circumstance that, if true, would render the accused’s actions lawful.
Each of these elements is subject to rigorous scrutiny by the court to determine whether the defence is valid.
Offences Where Mistake of Fact Applies
The defence of mistake of fact typically applies to strict liability offences, which do not require proof of intent (mens rea). Examples of such offences in Western Australia include:
- Persistent Sexual Contact with a Child Under 16 (Section 321A of the Criminal Code Act)
- The accused must have honestly and reasonably believed the child was 16 or older.
- The court will evaluate factors such as the child’s appearance, behaviour, and any representations made about their age.
- Showing Offensive Material to a Child Under 16 (Section 204A of the Criminal Code Act)
- This defence can be invoked where the accused mistakenly but reasonably believed the child was over 16.
- The court assesses whether the belief was reasonable under the circumstances.
- Certain charges within the Criminal Code Act Compilation Act 1913 (WA).
- Speeding Offences
- The defence may succeed if the accused can demonstrate a genuine and reasonable belief that their speedometer was functioning correctly, causing them to think they were within the speed limit.
Mistake of Law Not a Defence
It is important to distinguish between a mistake of fact and a mistake of law. Under Section 22 of the Criminal Code Act, a mistake about the law does not provide a defence. For example, ignorance of a law’s existence or misinterpreting its meaning will not exonerate an individual from criminal responsibility.
When a mistake involves both factual and legal elements, it will generally be treated as a mistake of law, thereby excluding the defence.
Onus of Proof
When the defence of mistake of fact is raised, the burden of proof operates as follows:
- Evidentiary Burden on the Defence: The accused must present sufficient evidence to show they held an honest and reasonable belief about the facts.
- Prosecution’s Burden to Disprove: Once the defence is raised, the prosecution must prove beyond a reasonable doubt that the belief was either not honest or not reasonable.
If the prosecution cannot disprove the defence, the accused cannot be convicted of the offence.
Case Review: The State of Western Australia v Anthonisz [2021] WASC 74
This case examines the mistake of fact defence under Western Australian criminal law, focusing on whether an accused person’s mistaken belief about a key fact can absolve them of criminal responsibility. It highlights the legal test for this defence and how courts determine whether a mistaken belief is both honest and reasonable.
Background
- Charge: The accused, Mr. Anthonisz, was charged with possession of a prohibited drug with intent to sell or supply.
- Defence Argument: Mr. Anthonisz claimed he mistakenly believed that the substance in his possession was not illegal, and therefore, he had no criminal intent.
- Key Context:
- The accused obtained the substance through a third party and asserted that he had no knowledge it was prohibited.
- His defence relied on Section 24 of the Criminal Code (WA), which states that a person is not criminally responsible if they act under an honest and reasonable, but mistaken, belief about a fact.
- The legal question was whether his mistaken belief was both honest and reasonable in the circumstances.
Court’s Findings
The Supreme Court of Western Australia found that:
- The honesty of the accused’s belief was not in dispute; there was evidence that he genuinely thought the substance was not illegal.
- However, the belief also needed to be reasonable—meaning a reasonable person in the same situation would have likely held the same mistaken belief.
- The court ruled that Mr. Anthonisz did not take sufficient steps to verify the legality of the substance, and his mistaken belief was therefore not reasonable under the law.
- As a result, the mistake of fact defence failed, and he was found guilty.
Legal Principles Highlighted
This case reinforces key aspects of the mistake of fact defence in Western Australian criminal law:
- Both Honest and Reasonable Belief Required: A mistaken belief must not only be genuinely held but also reasonable in the given circumstances.
- Burden of Proof: The accused must present evidence to show they had a reasonable basis for their mistaken belief.
- Due Diligence Matters: A failure to take reasonable steps to verify key facts can lead to the rejection of this defence.
The State of Western Australia v Anthonisz decision serves as a critical example of how courts apply the mistake of fact defence and what factors influence its success or failure in criminal cases.
**Please Note**
The material provided here is for informational use only and does not constitute binding legal advice. You should not use this information as a replacement for an individual consultation with a trained legal professional.
