What is Self-Defence?


What is Self-Defence?
Under Australian Criminal law, self-defence is a complete defence from criminal liability. A person may be exonerated from criminal responsibility for causing injury or even death in defence of his person; or defence of property (in a limited extent), or in defence of another person (normally a relative).

Note: Criminal law is primarily a state power, however the Commonwealth also exercises jurisdiction in some circumstances. The law in this area differs from state to state, and from Commonwealth to state.

Under the Commonwealth Criminal Code, Section 10.4(2), a person will not be held criminally responsible for an offence if the person is carrying out conduct in self-defence in the belief that the conduct was necessary:

(a)  to defend himself or herself or another person; or

(b)  to prevent or terminate the unlawful imprisonment of himself or herself or another person; or

(c)  to protect property from unlawful appropriation, destruction, damage or interference; or 

(d)  to prevent criminal trespass to any land or premises; or

(e)  to remove from any land or premises a person who is committing criminal trespass.

Self-Defence as a “Defence”

A person  is allowed to take any defensive or evasive steps that he believed necessary to protect their person against imminent danger. The determination whether the act is justified under the principle of self-defence depends upon the facts of the individual case.

In the case of Zecevic v DPP (1987) 162 CLR 645, the High Court found the act of killing a neighbour was justified after they (the accused and the deceased) had an argument and the accused believed that the deceased had a knife and a shotgun in his possession.

The High Court described self-defence as requiring…“ no set words or formula. The question to be asked in the end is simple. It is whether the accused believed upon reasonable grounds that it was necessary in self-defence to do what he did. If he had that belief and there were reasonable grounds for it, or if the jury is left in reasonable doubt about the matter, then he is entitled to an acquittal.”

Elements of Self-Defence

In the above case, the High Court defined the ‘reasonableness test’ as appropriate in self-defence for both homicide and non-homicide cases.

According to Wilson, Dawson and Toohey JJ, the determination lies as to whether the accused had reasonable grounds to believe that it was necessary to do what they did in self defence (Zecevic v DPP (1987) 162 CLR 645 at 661).

There are two elements to this test:

  • The accused must have had reasonable belief that the act was necessary at the time it was committed (the subjective test). This element requires the jury to determine whether there were reasonable grounds to believe that the act was necessary at the time the act was committed. In fulfilling this test, the jury puts itself in the shoes of the defendant.
  • The belief must have been based on reasonable grounds (the objective element). In determination of whether the accused’s belief was based on reasonable grounds, the jury can take into account:
  • the circumstances surrounding the offence and  the accused’s appreciation of the facts;
  • the relationship between the accused and the victim;
  • prior acts or behaviour of the victim;
  • the personal characteristics of the accused, his beliefs and present state of the mind
  • proportionality of the actions and weapons used by the accused; and
  • whether the accused had the chance to retreat, but failed or refused to do so.

When Self-defence is available

In essence, a person that carries out a conduct in self-defence is justified and may be absolve from any criminal liability if he believed the conduct was necessary under the following circumstances:

  • Defence of person.
  • Defence of property. This is to protect the property from unlawful appropriation, destruction, damage or interference; or to prevent criminal trespass to any land or premises; or to remove from any land or premises a person who is committing criminal trespass.
  • Defence of another person. In several instances, self defence was also used in the defence of another. Under the common law concept, self-defence of another is usually reserved for certain relationships that fell into the category where the victim is a relative (child and parent, wife and husband); or those under fiduciary relationship (master and servant). This is usually defined under state laws like Section 418(2)(a) of the Crimes Act 1900 (NSW); or Section 9AC, Section 9AE(a) of the Crimes Act 1958 (VIC); or Section 15(1) Criminal Law Consolidation Act 1935 (SA) and several other state laws.

Criminal law is the jurisdiction of both the States and the Commonwealth, jurisdiction depends on the offence and where it occurred. This article is a general discussion on the law of self defence, and draws mainly on the Commonwealth Criminal Code, and Victorian precedents. It is not a comprehensive overview of Commonwealth, State, or Territory law. The information contained in this article should not be relied upon in any way.


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