Published by Geoff Harrison | 5 July 2023
The law relating to when self-defence is available is set out in s418 of the Crimes Act 1900 (see below).
For an accused to rely upon self defence it must be properly raised, that is, there must be evidence capable of supporting a reasonable doubt in the mind of the tribunal of fact as to whether the prosecution has excluded self-defence: Colosimo v DPP  NSWCA 293 at . Hence, there is an evidential onus upon an accused to be able to point towards evidence of self defence. Once self defence is raised, it is then for the prosecution to prove beyond a reasonable doubt that the accused was not acting in self defence (s419 Crimes Act 1900); hence 'self defence' is not strictly a 'defence': R v Dziduch (1990) 47 A Crim R 378.
Self defence can also relate to a response to lawful conduct (s422 Crimes Act 1900). However, a significant and often important direction relating to self defence is the fact that, somebody acting in self defence, cannot weigh the exact measure of self defence when confronted with imminent danger (see Palmer  AC 814 at [831-832] and Zecevic at [662-663]). Nor does a person have to wait to be attacked before they are acting in self defence; a pre-emptive strike can be justified in circumstances of self defence (see Morgan v Colman (1981) 4 A Crim R 324 at 326 and Beckford  AC 130 at 144.
As stated by Simpson AJA in Doran at :
Where an issue under s 418 is raised, two questions arise for determination. They are:
(i) has the prosecution proved beyond reasonable doubt that the accused did not believe that the conduct said to constitute the offence was necessary for one (or more) of the four purposes specified in subss (2)(a)-(d)? and
(ii) has the prosecution proved beyond reasonable doubt that the conduct was not a reasonable response in the circumstance as perceived by the accused?
It arises invariably in every self defence case, that the prosecutor will put propositions that an accused could have walked away...this proposition negates the accused's subjective state of mind but, also discards the law that an accused has the right not to be assaulted and does not have to try to retreat before their actions will constitute self defence. The law also allows that a person does not have to wait to be attacked hence, a person does not have to retreat or walk anywhere.
CRIMES ACT 1900 - SECT 418
418 Self-defence--when available
(2) A person carries out conduct in self-defence if and only if the person believes the conduct is necessary-- (a) to defend himself or herself or another person, or (b) to prevent or terminate the unlawful deprivation of his or her liberty or the liberty of another person, or (c) to protect property from unlawful taking, destruction, damage or interference, or (d) 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.
Section 418 changes the common law relating to self defence as set out in Zecevic v Director of Public Prosecutions (Vic)  HCA 26; (1987) 162 CLR 645. The questions to be answered by the tribunal of fact under s418 were set out by Howie J in R v Katarzynski  NSWSC 613 (9 July 2002) at -:
22 The question now posed for the jury, where there is evidence raising self-defence, is not the same as it was at common law after Zecevic v DPP and as it was considered in Conlon. The questions to be asked by the jury under s 418 are: (i) is there is a reasonable possibility that the accused believed that his or her conduct was necessary in order to defend himself or herself; and, (2) if there is, is there also a reasonable possibility that what the accused did was a reasonable response to the circumstances as he or she perceived them.
23 The first issue is determined from a completely subjective point of view considering all the personal characteristics of the accused at the time he or she carried out the conduct. The second issue is determined by an entirely objective assessment of the proportionality of the accused’s response to the situation the accused subjectively believed he or she faced. The Crown will negative self-defence if it proves beyond reasonable doubt either (i) that the accused did not genuinely believe that it was necessary to act as he or she did in his or her own defence or (ii) that what the accused did was not a reasonable response to the danger, as he or she perceived it to be.
24 The issue as to the reasonableness of the accused’s response is objective in so far as the jury is not concerned with what the accused believed was necessary to respond to the circumstances as he or she perceived them to be. The current provision is not concerned with whether the accused’s belief as to what was the necessary response was a reasonable one or whether he or she had reasonable grounds for that belief. This is where the current provisions are in contrast to the position at common law: the accused need not have reasonable grounds for his or her belief that it was necessary to act in the way he or she did in order to defend himself or herself. It is sufficient if the accused genuinely holds that belief.
25 It will be a matter for the jury to decide what matters it should take into account when determining whether the response of the accused was reasonable in the circumstances in which he or she found himself or herself. The jury is not assessing the response of the ordinary or reasonable person but the response of the accused. In making that assessment it is obvious than some of the personal attributes of the accused will be relevant just as will be some of the surrounding physical circumstances in which the accused acted. So matters such as the age of the accused, his or her gender, or the state of his or her health may be regarded by the jury. Whether or not some particular personal characteristic of the accused is to be considered will depend largely upon the particular facts of the case.
26 But in my opinion one matter that must be irrelevant to an assessment of the reasonableness of the accused’s response is his or her state of sobriety. As was pointed out in McCullough, it is logically incongruous “to contemplate the proposition that a person's exercise of judgment might be unreasonable if he was sober, but reasonable because he was drunk”. Apart from Conlon, I am not aware of any other decision that has held that intoxication is a matter relevant to an evaluation of the reasonableness of the conduct or belief of a person. It is not relevant at common law to an evaluation of the accused’s response to provocation or the belief of a reasonable person as to the dangerousness of the accused’s actions for the offence of manslaughter.
27 In Conlon Hunt CJ at CL expressed the view that he was not prepared to introduce the policy applied in the interpretation of s 46 of the Tasmanian Code in McCullough to the interpretation of the decision in Zecevic v DPP. I do not believe that I am similarly constrained. As I have indicated s 418 is not, and was not intended to be, a codification of the common law. Further, the general policy adopted by the legislature in respect of the relevance of intoxication to the criminal law is contained in Part 11A of the Crimes Act. The provisions of that Part have limited the use that a court can make of the fact that an accused is intoxicated when considering criminal responsibility. In my view, if the policy enunciated in Part 11A were not adopted in construing s 418, the result would be to create an illogical and unacceptable inconsistency in the criminal law of this State with regard to the relevance of intoxication to criminal responsibility.
28 For these reasons I directed the jury to the effect that they must take into account the accused’s intoxication when considering whether he might have believed that it was necessary to act as he did in defence of himself and when considering the circumstances as he perceived them, but not when assessing whether his response to those circumstances was reasonable.
The Bench Book sets out the following essential components when considering self defence:
[6-455] Essential components of self-defence direction:
A direction for self-defence in cases other than murder must contain the following essential components:
1. The law recognises the right of a person to act in self-defence from an attack or threatened attack.
2. It is for the Crown to eliminate it as an issue by proving beyond reasonable doubt that the accused’s act was not done in self-defence.
3. The Crown may do this by proving beyond reasonable doubt either:
(a) the accused did not believe at the time of the act that it was necessary to do what he or she did in order to defend himself or herself; or
(b) the accused’s act was not a reasonable response in the circumstances as he or she perceived them.
4. In determining the issue of whether the accused personally believed that his or her conduct was necessary for self-defence, the jury must consider the circumstances as the accused perceived them to be at the time.
5. If the jury is not satisfied beyond reasonable doubt that the accused did not personally believe that his or her conduct was necessary for self-defence, it must then decide whether the Crown has proved beyond reasonable doubt that the conduct of the accused was not a reasonable response to the circumstances as perceived by him or her. If the Crown fails to do so it will have failed to eliminate self-defence.
6. If the Crown fails to prove both numbers 3(a) or (b), it will have failed to eliminate self-defence. If it proves one or the other, it will have succeeded.
A direction for self-defence in cases of murder must contain all the above numbers 1-5 essential components. The difference is that they are applied to the facts in a sequential way to accommodate the offence of manslaughter by excessive self-defence.
1. The jury is instructed as to numbers 1–2 above. It must first specifically consider self-defence on the charge of murder. The jury must be instructed in terms of number 3(a) above — that if the Crown has not proved beyond reasonable doubt that the accused did not believe that it was necessary to do what he or she did then the appropriate verdict is one of “not guilty of murder”.
2. Number 3(b) above is then considered, that is, whether the accused’s act was not a reasonable response in the circumstances as he or she perceived them.
3. If the jury finds that the Crown has failed to prove beyond reasonable doubt that the accused’s act was not a reasonable response in the circumstances as he or she perceived them, the Crown will have completely failed to eliminate self-defence. In that situation the jury is instructed to also return a verdict of “not guilty of manslaughter”.
4. However a verdict “not guilty of murder but guilty of manslaughter” can be returned if the Crown prove beyond reasonable doubt that the conduct of the accused was not a reasonable response in the circumstances as the accused perceived them because the particular use of force by the accused was excessive or otherwise unreasonable. Such a verdict can be returned providing the jury is satisfied beyond reasonable doubt of the other elements.
See also the discussion of Hadchiti v The Queen (2016) 93 NSWLR 671 and Moore v R  NSWCCA 185 at [3-603] Notes. Both cases were concerned with appropriate directions for self-defence in question trails.