Mistake of Fact (ACT)

By James Stevens, Director and Solicitor, Go To Court Lawyers. Last reviewed 20 April 2026.

The defence of mistake of fact can be utilized in cases involving strict liability offences. In the ACT, this defence can also be applied in certain circumstances to other offences, as outlined in sections 35 and 36 of the Criminal Code 2002. This article focuses on the application of the defence of mistake of fact in the ACT.

Legislation on mistake of fact in the ACT

Under section 35 of the Criminal Code, an individual is not criminally liable for an offence with a fault element other than negligence in the ACT if:

• They held a mistaken belief about, or were unaware of, the facts when they committed the physical act; and
• The mistaken belief negates intention.

Under section 36 of the Criminal Code, an individual is not criminally liable for an offence without a fault element if:

• The accused considered whether or not certain facts existed when committing the physical act and
• They held a mistaken belief about those facts; and
• Had their belief been correct, their conduct would not have constituted an offence.

Strict Liability Offences

Strict liability offences are offences that do not have a fault element. This means that an individual can be found guilty even if they did not intend to commit the offence. Strict liability offences only require the prosecution to prove that the accused committed the physical elements of the offence.

Traffic offences and offences involving breaches of family violence orders and apprehended violence orders are examples of strict liability offences. These offences do not require proof that the accused intended or foresaw the commission of the offence; only that they committed the acts alleged in the circumstances alleged.

Strict liability offences in the ACT include:

• Speeding
• Breach of AVO or FVO
• Offences involving sexual contact with a child under 16

Using the mistake of fact defence

In cases involving strict liability offences, the defence of mistake of fact can be utilized as follows:

Speeding

If a person is caught driving at 70km/h in an area where the speed limit is 60km/h, but according to their speedometer, they were traveling at 60km/h, the accused could argue that they believed their speedometer to be accurate. However, this defence would not be successful if the person had been traveling at 100 km/h where the speed limit is 60km/h as the belief that the vehicle was not speeding in that situation would not be reasonable.

Breach AVO

If a person is charged with breaching a family violence order and found to be present at premises where the protected person is working, the accused could argue that they had a mistaken belief that the protected person did not work at that location if they had reason to believe this was the case.

Child Sex Offences

If a person is charged with having sexual contact with a child under 16, but the child in question had told the accused that they were 16, the accused could argue that they honestly but mistakenly believed the child was over 16. However, this defence would be less likely to succeed the younger the child was because the mistake must be reasonable as well as honest.

Mistake of fact not mistake of law

It is important to note that the defence of mistake of fact does not apply to mistakes of law. If an accused person is mistaken about the law, this does not excuse them from responsibility for an offence. If a person is mistaken about a circumstance that is a combination of fact and law, it is considered a mistake of law.

Case law on mistake of fact

Several court decisions have considered the defence of mistake of fact. Some of these decisions are summarized below.

Proudman v Dayman (1941)

This decision established that the accused must have a positive belief, not mere ignorance.

He Kaw Te v The Queen (1985)

This decision further established that the accused must have expressly turned their mind to a fact and made a mistake about it. It is not enough for them not to have considered the matter at all.

Mei Ying Su and Others v Australian Fisheries Management Authority and Another (2008)

This decision established that the defence of mistake of fact does not involve the ‘ordinary person’ test. The belief must have been a belief of the accused’s and be objectively reasonable. Reasonableness is to be assessed in relation to the accused’ subjective circumstances such as their personal attributes and the information they had at the time of the alleged offence.

If you require legal advice or representation in any legal matter, please contact Armstrong Legal.

8