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Assault in Self Defence


In NSW it is an offence to physically assault, cause harm to or injure someone. A person also commits the offence of assault if they threaten someone to the extent that the victim believes physical violence or harm is imminent. There are many different types of assault offences in New South Wales. These offences range from minor assaults, including common assault to very serious assaults, such as inflicting grievous bodily harm with intent, which carries a maximum penalty of 25 years imprisonment. It is a full defence to any assault offence if the accused acted in self-defence and what they did was reasonable in the circumstances.

The Defence Of Self-Defence

Under NSW legislation, a person who successfully shows that they acted in self-defence will be acquitted of an assault offence. Division 3 of Part 11 of the Crimes Act 1900 contains a number of provisions concerning this defence. The primary provision is section 418 which states:

  • A person is not criminally responsible for an offence if the person carries out the conduct constituting the offence in self-defence.
  • A person carries out conduct in self-defence if and only if the person believes the conduct is necessary:
    • to defend himself or herself or another person, or
    • to prevent or terminate the unlawful deprivation of his or her liberty or the liberty of another person, or
    • to protect property from unlawful taking, destruction, damage or interfere, or
    • to prevent criminal trespass to any land or premises or to remove a person committing any such criminal trespass, and the conduct is a reasonable response in the circumstances as he or she perceives them.

When Will The Defence of Self Defence Succeed?

To raise the defence of self-defence you need to enter a plea of not guilty. Your matter will then proceed to a hearing or trial in which you can raise self-defence as the reason for your conduct which might otherwise have constituted the offence of assault. The prosecution will then need to prove that you were not acting in self-defence.

Self-defence can be raised by arguing:

  • That the accused committed the assault to defend themself or another person;
  • That they committed the assault because they or another person were being falsely imprisoned or held captive by someone else;
  • To argue that they committed the assault because they were protecting the property from theft, destruction or damage; and
  • To argue that they committed the assault because they were preventing someone from trespassing or removing a person who was trespassing.

Importantly, self-defence will only be successful if what the accused did was reasonable in the circumstances. This means that the response must have been proportionate to the threat, harm or crimes that they were responding to. For example, shooting someone who shoves you in the chest, or even punches or attacks you is unlikely to be found to be a reasonable response. Similarly, injuring a person who is trespassing on your property is unlikely to be reasonable. However, it all depends on the circumstances of the case.

What Assaults Might Be Done In Self Defence?

Examples of cases where self-defence can be successfully raised by someone charged with assault include:

  • Punching a person who is hitting and punching you to get them to stop;
  • Walking down a laneway and tackling the man you see beating and sexually assaulting a woman;
  • Pushing someone in the chest because they are walking towards you, are very aggressive and are yelling, “I’m going to kill you!”; and
  • Telling someone who has just poured petrol around a house not to set fire to it and then pushing them over and grabbing the lighter from their hand.

What The Police Must Prove

If a person is charged with an assault offence and raises self-defence, the police must negate the defence, that is to prove that what occurred was not actually done in self-defence. To prove that the accused was not acting in self-defence, the police will need to prove beyond a reasonable doubt:

  • That the accused’s response was not reasonable in the circumstances; and
  • Depending on which form of self-defence is raised:
    • That when they committed the assault, they were not defending themself or another person;
    • That when they committed the assault, they or another person were not being falsely imprisoned or held captive by someone else;
    • That when they committed the assault, they were not protecting property from theft, destruction or damage; or
    • That when they committed the assault, they were not preventing someone from trespassing or removing a person who was trespassing.

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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