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The Defence of Self Defence (ACT)

Self-defence is a defence to any violent offence, including murder and manslaughter. If the court accepts that the accused was acting in self-defence, it will dismiss the charge. Once a defence of self-defence has been raised, the onus is on the prosecution to disprove it beyond a reasonable doubt.


The self-defence law for the ACT is found in Section 42 of the Criminal Code Act 2002, which provides:

  • A person is not criminally responsible for an offence if the person carries out the conduct required for the offence in self-defence.
  • A person carries out conduct in self-defence only if:
    • the person believes the conduct is necessary to defend himself or herself or someone else; or
    • to prevent or end the unlawful imprisonment of himself or herself or someone else; or
    • to protect property from unlawful appropriation, destruction, damage or interference; or
    • to prevent criminal trespass to land or premises; or
    • to remove from land or premises a person committing criminal trespass.

    The conduct has to be a reasonable response in the circumstances as the person perceives them.

  • However, the person does not carry out conduct in self-defence if:
    • the person uses force that involves the intentional infliction of death or serious harm to protect property, or to prevent criminal trespass or to remove a person committing criminal trespass; or
    • the person is responding to lawful conduct that the person knows is lawful.

Burden of proof

The ultimate onus of proof in relation to self-defence does not rest on the accused. In Zecevic v DPP (Vic) (1987) 162 CLR 645, Justices Wilson, Dawson and Toohey said, “It has been clearly established that once the evidence discloses the possibility that the … act was done in self-defence , a burden falls upon the prosecution to disprove that fact, that is to say, to prove beyond reasonable doubt that the … act was not done in self-defence. The jury must be instructed accordingly whether or not the plea is actually raised by the accused.”

The prosecution must show either:

  • that the accused did not genuinely believe that it was necessary to act as he or she did in his or her own defence; or
  • that what the accused did was not a reasonable response to the danger, as he or she perceived it to be.


There are two questions to be answered by the court when self-defence is raised. These are:

    • Is there a reasonable possibility that the accused believed that his or her conduct was necessary in order to defend himself or herself?; and
    • If there is, is there also a reasonable possibility that what the accused did was a reasonable response to the circumstances as he or she perceived them?

The first question is determined subjectively, considering the personal characteristics of the accused at the time they carried out the conduct.

The second question is determined objectively, assessing the proportionality of the accused’s response to the situation they believed they faced.

The accused must have had a genuine belief they needed to act in the way they did to defend themselves.

The jury is not assessing the response of the reasonable person but the response of the accused. Matters such as the accused’s age, gender, or health can be regarded by the jury (or judge or magistrate).

Pre-Emptive Strike, Retreat and Defence of Another

The defence of self-defence can apply to a pre-emptive strike to an attack. Australian courts have generally found that the belief needs to be reasonable, as objectively viewed.

A person is entitled to use the same amount of force in the defence of another person from imminent attack as they are allowed to use if the attack were aimed at them. This applies regardless of whether the other person is a “relative, friend or stranger”: R v Portelli (2004) 10 VR 259 per Ormiston, JA.

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

Michelle Makela

This article was written by Michelle Makela

Michelle has over 15 years experience in the legal industry, working across commercial litigation, criminal law, family law and estate planning.  Michelle has been involved in all practice areas of the firm and in her personal practice has had experience in litigation at all levels (State and Federal Industrial Tribunals, the Supreme Court, Court of Appeal, the Federal Court, Federal...

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