The most common legal defence to offences involving the use of force is self-defence. Self-defence is a legal defence that recognises that an individual cannot be expected to remain passive in the face of a physical attack or threatened attack and that people are entitled to defend themselves against unlawful violence. This page deals with the defence of self-defence in New South Wales.
Legislation
In New South Wales, the defence of self-defence is set out in section 418 of the Crimes Act 1900. Under that provision, a person is not guilty of an offence if they carry out conduct in self-defence believing that the conduct is necessary to:
- defend themselves or another person;
- prevent or terminate the unlawful deprivation or liberty of a person;
- protect property from unlawful taking, destruction, interference or damage;
- prevent criminal trespass to land or premises or remove a person trespassing;
AND the conduct is a reasonable response to the circumstances as the person perceives them.
When is self-defence available?
The defence of self-defence is available to all offences involving the use of force. This includes assault, causing grievous bodily harm, manslaughter and murder. However, in order for self-defence to succeed, the defensive conduct must be proportionate to the nature and extent of the threat that the accused believed they were facing.
In order to successfully rely on self-defence in relation to a serious charge such as murder or manslaughter, the defence will need to show that the accused was faced with a very serious threat to their life or to someone else’s life.
Proportionality
A person who is faced with a physical threat is not expected to weigh the exact level of force that is justified ‘on a knife’s edge’. Rather, their response is to be assessed in the circumstances as they perceived them at the time and not with the benefit of hindsight.
Excessive force
If a person kills another person under circumstances where the threat posed to the accused did not warrant the use of lethal force, a partial defence of excessive force can be relied on. This partial defence can be used to reduce a charge of murder to one of manslaughter.
Zecevic v DPP
The leading case on the defence of self-defence is the 1987 High Court of Australia decision of Zecevic v DPP. In that case, the accused was charged with murder after killing his neighbour. He relied on the defence of self-defence, arguing that he believed that his actions were necessary in self-defence.
The accused had held an honest belief that the neighbour was armed with a knife and a shotgun and had retrieved his own gun and shot the man.
The court summarized the test for self-defence as follows:
“The question to be asked in the end is quite 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.”
The test set out in the decision of Zecevic v DPP for assessing whether a person acted in self-defence is therefore partly subjective and partly objective. First, the court must consider whether the accused had a reasonable belief that they needed to act as they did in self-defence. This is a subjective question. Second, the court must consider whether there were reasonable grounds for that belief. This is an objective test.
When can self-defence not be used?
A person cannot rely on the defence of self-defence if they instigated the encounter.
Burden of proof
The defence has the burden of raising self-defence. Once self-defence has been raised, the burden shifts to the prosecution. The prosecution must prove that the accused was not acting in self-defence.
Effect of self-defence
Self-defence is a full defence to any offence involving the unlawful use of force. This means that if a person is found to have acted in self-defence, they will be acquitted as their actions did not amount to an offence. In other words, self-defence renders lawful conduct that would otherwise amount to a criminal offence.
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