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4. Excessive self-defence

56 THE PARTIAL DEFENCE OF EXCESSIVE SELF-DEFENCE reduces murder

to manslaughter where the defendant intended to act in self-defence but in doing so used more force than was reasonable. It was introduced to Australian law by the High Court of Australia in R v Howe,[71] rejected by the Privy Council in Palmer v R[72] (on appeal from the Jamaican Court of Appeal), re-established by the High Court of Australia in Viro v R[73] (not following the Privy Council), re-considered by the High Court of Australia in Zecevic v R[74] and abolished by a five to two majority. Currently it is available

in South Australia (by statute),[75] in India (as part of the Penal Code),[76]

in Sudan (as part of its Penal Code),[77] and in Ireland (as a common law defence).[78]

57 The underlying rationale for the defence is:[79]

... to be found in a conviction that the moral culpability of a person who kills another in defending himself but who fails in a plea of self-defence only because the force which he believed to be necessary exceeded that which was reasonably necessary falls short of the moral culpability ordinarily associated with murder. The notion that a person commits murder in these circumstances should be rejected on the ground that the result is unjust. It is more consistent with the distinction which the criminal law makes between murder and manslaughter that an error of judgment on the part of the accused which alone deprives him of the absolute shield of self-defence results in the offence of manslaughter.

58 Various forms of the defence have been proposed, a number of which are set out below.

59 In the Australian High Court case of Viro v R, Mason J set out a jury direction for excessive self-defence:[80]

(1) (a) It is for the jury first to consider whether when the accused killed the deceased the accused reasonably believed that an unlawful attack which threatened him with death or serious bodily harm was being or was about to be made upon him.

(b) By the expression “reasonably believed” is meant, not what a reasonable man would have believed, but what the accused himself might reasonably believe in all the circumstances in which he found himself.

(2) If the jury is satisfied beyond reasonable doubt that there was no reasonable belief by the accused of such an attack no question of self-defence arises.

(3) If the jury is not satisfied beyond reasonable doubt that there was no such reasonable belief by the accused, it must then consider whether the force in fact used by the defendant was reasonably proportionate to the danger which he believed he faced.

(4) If the jury is not satisfied beyond reasonable doubt that more force was used than was reasonably proportionate it should acquit.

(5) If the jury is satisfied beyond reasonable doubt that more force was used, then its verdict should be either manslaughter or murder, that depending upon the answer to the final question for the jury – did the accused believe that the force which he used was reasonably proportionate to the danger which he believed he faced?

(6) If the jury is satisfied beyond reasonable doubt that the accused did not have such a belief the verdict will be murder. If it is not satisfied beyond reasonable doubt that the accused did not have that belief the verdict will be manslaughter.

60 The Criminal Law Revision Committee of England and Wales, having recommended that the common law defence of self-defence be codified along the lines of section 48 of our Crimes Act 1961, also recommended a new defence reducing murder to manslaughter:[81]

Where a person kills in a situation in which it is reasonable for some force to be used in self-defence or in the prevention of crime but the defendant uses excessive force, he should be liable to be convicted of manslaughter not murder, if, at the time of the act, he honestly believed that the force he used was reasonable in the circumstances.

A similar formulation appears in the draft Criminal Code⁸² and has the support of the House of Lords Select Committee on Murder and Life Imprisonment.[83]

61 Section 15 of the Criminal Law Consolidation Act 1935 (South Australia) provides:

(1) It is a defence to a charge of an offence if –

(a) the defendant genuinely believed the conduct to which the charge relates to be necessary and reasonable for a defensive purpose; and

(b) the conduct was, in the circumstances as the defendant genuinely believed them to be, reasonably proportionate to the threat that the defendant genuinely believed to exist.

(2) It is a partial defence to a charge of murder (reducing the offence to manslaughter) if –

(a) the defendant genuinely believed the conduct to which the charge relates to be necessary and reasonable for a defensive purpose; but

(b) the conduct was not, in the circumstances as the defendant genuinely believed them to be, reasonably proportionate to the threat that the defendant genuinely believed to exist.

62 A New Zealand provision could be drafted around the words of section 48 of the Crimes Act 1961. For example:

It is a partial defence to a charge of murder (reducing the offence to manslaughter) if, in the defence of himself or herself or another, a person uses more force than it is reasonable to use in the circumstances as he or she believes them to be.

Advantage of the defence

63 The advantage of the defence is that it recognises that a person who kills, believing (wrongly) that this is necessary in self-defence, is less culpable than a person who kills with no such belief. A partial defence of excessive self-defence would take into account the subjective perception that prompted the defendant’s action, without abandoning the boundaries of acceptable conduct that society has a right to expect from all citizens.

64 It has been said that a qualified defence may prevent a jury giving a complete acquittal out of sympathy in cases where it considers that the defendant acted honestly but unreasonably.[84] This argument is particularly strong where there is a mandatory sentence of life imprisonment for murder.

Disadvantage of the defence

65 The Model Criminal Code Officers Standing Committee was of the opinion that, while simple tests for excessive self-defence could and had been developed, such tests offered insufficient guidance to a jury.[85] Attempts to develop guidance for judges directing juries on excessive self-defence have resulted in complicated formulae more apt to confuse than assist. A major factor in the abolition of the doctrine by the Australian High Court in Zecevic was that the instruction devised in Viro was too difficult for juries to understand. The author of the test, Mason J, did not think that a reformulation of his propositions would help and that, accordingly, there was a serious risk of the doctrine not operating the way it was intended.[86]

Is the defence necessary?

66 It has been suggested that a partial defence of excessive self-defence is unnecessary because the facts giving rise to such a defence may well also go to prove provocation.[87] Further, the Crown has to prove that the defendant’s use of force was not reasonable and a jury would be slow to accept this if the defendant honestly believed the force used to be necessary.[88]

Question 3: Should a new partial defence of excessive self-defence be introduced in New Zealand?