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The Defence of Self-Defence

Self-defence is a defence that is commonly relied on in response to an assault charge. The defence is also available for all offences involving the unlawful use of force. A person is not guilty of an offence if they were acting in defence of themselves or of another person. This article outlines the operation of the defence of self-defence in New South Wales.


Section 418 of the Crimes Act 1900 outlines when self-defence is available in New South Wales. Under that provision, the accused must have believed their conduct was necessary to:

  1. defend themselves or another person; or
  2. prevent or terminate the unlawful deprivation of their liberty or the liberty of another person; or
  3. protect property from unlawful taking, destruction, damage or interference; or
  4. prevent criminal trespass to any land or premises or to remove a person committing any such criminal trespass; AND
  5. the conduct must have been a reasonable response in the circumstances as the accused perceived them.

Subjective and objective test

The test for self-defence is a ‘two-limb test’ and includes both a subjective and an objective element.

Firstly, the court needs to consider whether the accused had a subjective belief that their actions were necessary in self-defence. In assessing this, the court must take into account the accused’s age, gender, health, mental health and relevant experiences (for example whether they had previously been a victim of violence). If the court is satisfied that the accused believed their conduct was necessary, the first limb is made out.

Secondly, the court must consider whether the accused’s conduct was a reasonable response to the circumstances as they perceived them. This involves an objective assessment of what was reasonable in the circumstances. However, the objective determination of whether a response was reasonable must be applied through the lens of what the accused perceived at the relevant time.

Onus Of Proof for Self-Defence

When a person is charged with an offence and wants to rely on self-defence, they or their legal representative bears the burden of raising self-defence on the balance of probabilities. This means that the finder of fact must be satisfied that it is more likely than not that the person was acting in self-defence.

Once self-defence has been raised by the defence, the burden then shifts back to the prosecution to negate self-defence. To do this the prosecution must prove beyond a reasonable doubt that either:

  1. the accused did not genuinely believe that their conduct was necessary; or
  2. the conduct was not a reasonable response to the circumstances as the accused perceived them.

The prosecution is required to negate only one of these two limbs in order for the defence to be defeated.

When is Self-Defence Not Available?

The defence of self-defence is not available if the accused applied physical force that resulted, either intentionally or recklessly, in death and the conduct was done to protect property or to prevent criminal trespass.

Partial defence of excessive self-defence

Where a person uses excessive force in self-defence and causes the death of another person, they may be found not guilty of murder but guilty of manslaughter. In other words, excessive self-defence may be relied on as a partial defence, but not as a full defence.


Intoxication is not a criminal defence. However, it can be a factor when assessing whether a criminal defence is made out.

Where a person relies on the defence of self-defence in relation to an act that was committed when they were intoxicated, their intoxication is relevant to assessing the first limb of the test for self-defence.

When the court is assessing whether the accused believed their conduct was necessary, it may have regard to the accused’s intoxication. However, when the court moves on to considering the second limb of the test, it must not have regard to the accused’s intoxication. The court must assess whether the accused’s actions were a reasonable response to the circumstances as the accused perceived them. It must consider this question without reference to the accused’s intoxication.

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

Cara Maynard - Senior Associate – Canberra

This article was written by Cara Maynard - Senior Associate – Canberra

Before joining the team at Armstrong Legal, Cara worked as a DNA expert preparing and giving DNA evidence in criminal trials. In this role she liaised with police, DPP and defence practitioner regarding a variety of matters including DNA transfer, deposition and recovery. Cara has reviewed and interpreted thousands of DNA profiles that were reported as intelligence to the NSW...

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