In New South Wales the law as to self-defence is essentially contained in Section 418 of the Crimes Act 1900 and there are various case authorities that interpret that section.
Essentially, there are two (2) legs to making out a defence of self-defence and they are:
- The person who asserts he or she is acting in self-defence has to believe that the action taken was necessary to defend himself or herself or another person; and
- The conduct or actions of the person have to have been reasonably proportionate to the perceived threat.
As to the first question, that is, whether there is a reasonable possibility that the accused believed that his or her conduct was necessary in order to defend himself or herself, that question is determined from a completely subjective point of view, having regard to all the personal characteristics of the accused at the time he or she carried out the conduct. This would include the accused being affected by alcohol and/or drugs or having a mental health issue which may cause him or her to have a “short fuse”.
As to the second question, it is determined entirely by an objective assessment of the proportionality of the accused’s response to the situation he or she believed he or she faced. Put another way, the prosecution would have to prove beyond reasonable doubt, that the actions taken by the accused, in purported self-defence, were not reasonable in the circumstances.
Take for example, an intruder into your home. You startle the intruder and he immediately flees running out into the backyard and about to climb a fence. You fire a gun and shoot the intruder. Clearly, that would not be self-defence because, even assuming you get over the first leg, that is, that you believed it was necessary for you to fire the gun; you would certainly fail in respect of the more difficult second leg (that the firing of the gun was proportionate to the threat) and more particularly, the prosecution would be able to prove that your actions in firing the gun were not reasonable.
Having said that, the case law is also clear that pre-emptory actions can still amount to self-defence and you don’t have to wait for someone to hit you if your perception is that that is what was going to happen. Put another way, if you are approached aggressively in a bar and the other person has his fists raised and clenched and it appeared to you that he was about to strike you, you would be entitled to take [reasonable] action to prevent him striking you. That action may include you striking him first or taking other “defensive” action.
The law of self-defence can sometimes be quite complex and it is important to get legal advice early.