In the criminal law of Australia, self-defence is a legal defence to a charge of causing injury or death in defence of the person or, to a limited extent, property, or a partial defence to murder if the degree of force used was excessive.
Self-defence in murder
In Viro v The Queen, Justice Mason formulated six propositions on the law of self-defence in murder trials. Thus, a full acquittal is achieved if the jury finds that an accused reasonably believed they were threatened with death or serious bodily harm and, if so, that the force used was reasonably proportionate to the perceived danger. In Zecevic v Director of Public Prosecutions, the victim rented a unit from the defendant. The defendant became increasingly annoyed with the victim who kept leaving the security gates of the unit unlocked. After one heated exchange, the defendant was stabbed by the tenant. The defendant, fearing that the tenant was about to get a gun from his car, rushed off and got his shotgun. The defendant returned, and shot and killed the tenant. The majority of the High Court said at 661: The New South Wales Court of Criminal Appeal in R v Burgess; R v Saunders held that 'the concept of self-defence only arises where the actions of the accused by way of self-defence are directly taken against the person threatening the accused or another’s being or property.' In R v Conlon the accused used a shotgun to repel two trespassers whom he believed to be stealing his cannabis plants. His belief was affected by drunkenness and a schizoid personality disorder which were relevant to determine whether the Crown had proved that he had not acted in self defence: specifically whether he believed that it was necessary to do what he did and whether that was a reasonable belief. This question seems advantageous to the defence because it tests whether the belief is reasonable to the accused, not reasonable to the reasonable person. In NSW, ss 418-423 of the Crimes Act 1900 now govern the law relating to self-defence and excessive self-defence. Under South Australian law, the general defence appears in s15 Criminal Law Consolidation Act 1935 for defending a person's life, and s15A for defending property, subject to a hybrid test, i.e. the defendant honestly believed the threat to be imminent and made an objectively reasonable and proportionate response to the circumstances as the accused subjectively perceived them. In July 2003, the Rann Government introduced laws allowing householders to use "whatever force they deem necessary" when confronted with a home invader. Householders who kill or injure a home invader escape prosecution provided they can prove they had a genuine belief that it was necessary to do so to protect themselves or their family. The law was strongly opposed by then-Director of Public Prosecutions Paul Rofe,, and lawyer Marie Shaw, who is now a District Court Judge.
Excessive force
The rationale of the defence recognises that the degree of culpability normally associated with murder may be missing. In the High Court case of Viro v The Queen, Aickin J said: The defence was first recognised in the common law in R v McKay, where a farmer shot and fatally wounded a chicken thief, and confirmed in R v Howe where Mayo J held at 121-122: This mitigatory defence was abolished in Zecevic v Director of Public Prosecutions which expressed the view that provocation should be the alternative considered. The defence was re-introduced in statutory form in South Australia in 1991, revised in 1997. The Criminal Law Consolidation Act 1935 s15 now reads: s15A extends the partial defence to circumstances where the accused had applied excessive force in killing the deceased but had genuinely believed the force to be necessary and reasonable: In 2002, New South Wales reintroduced excessive self defence as s421 of the Crimes Act 1900. Section 421 states: otherwise criminally responsible for manslaughter. Unlike South Australian law, s420 of the NSW Crimes Act explicitly states that self-defence is not available as a defence to murder if death is inflicted to prevent criminal trespass. In November 2005, pursuant to recommendations from the Law Reform Commission for Victoria, the Victorian legislature introduced new laws regarding self defence. Among them, a new offence of defensive homicide was created: where the accused's belief in the need for the force applied in self-defence was unreasonable, s/he may be convicted of an offence less serious than murder. However, defensive homicide was abolished in November 2014.
