Chapter 8
Partial defences and separate homicide offences

Partial defences

8.15Jurisdictions comparable to New Zealand have used a range of partial defences to reflect culpability for homicide that is considered to be less than murder, and several of these could apply where a victim of family violence kills their abuser.

8.16The most notorious of these partial defences is provocation, which was developed to reflect the social norms that existed at the time of its enactment.445 As it was the only partial defence available in New Zealand, it was relied on by victims of family violence who had killed the primary perpetrator of the violence.446 In essence, that required the defendant to claim that they had “snapped” as a result of sustained and repeated violence from the deceased.
8.17However, in practice, the primary users of the partial defence of provocation were men who had a disposition to violence and who reacted to a slight or insult or unwanted advance by striking out with lethal force. As a consequence, the Law Commission recommended the abolition of the defence in 2001 and 2007.447 We do not consider there is good reason to revisit the decision of Parliament to abolish the partial defence of provocation, although we do consider the option of “loss of control” below. There are several other partial defences that have developed in other jurisdictions, which we are seeking feedback on.

Excessive self-defence

8.18Excessive self-defence would apply when a person uses excessive force to defend themselves or another. Defendants in this category would satisfy the first limb of self-defence in that they would have been acting to defend themselves or another. However, they would fail to meet the second limb because they used a level of force that was not reasonable. At present, a person who uses excessive force in response to a threat is at risk of conviction for murder unless they lacked the necessary murderous intent.

8.19Excessive self-defence as a partial defence exists in the jurisdictions of New South Wales,448 South Australia449 and Western Australia.450 The separate offence of “defensive homicide”, in force in Victoria from 2005 to 2014, was also, in essence, a partial defence to murder based on excessive self-defence. That is discussed in more detail below.
8.20In 2001, the Law Commission concluded that, of all the partial defences it considered, this was the one it would most favour introducing into New Zealand law:451

In provocation and diminished responsibility, the defendant intends to do something that is unlawful. In excessive self-defence, the defendant intends to do something that is lawful within limits. Being closely aligned with the elements of self-defence, it would not involve completely new concepts. Excessive self-defence would only arise when self-defence is a jury issue and would fit easily and naturally into jury directions on self-defence. We do not think that the New Zealand version of the defence would entail the complexities that were associated with the defence in Australia. Further, the link between self-defence and excessive self-defence means it is more appropriate to the circumstances that are typical of the cases involving battered defendants than provocation or diminished responsibility.

8.21However, the Commission ultimately preferred to rely on a sentencing discretion for murder to accommodate the many and various situations when a lesser culpability in intentional homicide should be recognised.452

Loss of controlTop

8.22This partial defence would be modelled on the English legislation that came into force in 2010,453 discussed in Chapter 6 at paragraphs 6.50–6.51. The loss of control defence replaced the defence of provocation. While the two defences have similar elements in that they both envisage a reasonable person acting as a result of being seriously wronged by a “qualifying trigger”, the new defence is limited to “gross provocation” and specifically excludes sexual infidelity as a reason to invoke the defence.
8.23The Law Commission for England and Wales considered that the new defence would be of more value to victims of family violence than the defence of provocation. It applies where a defendant’s loss of self-control is attributable to the defendant’s fear of serious violence from the deceased (against the defendant or another identified person).454 There is no need for the defendant’s loss of self-control to be sudden and overwhelming; it could be a result of sustained violence or fear of violence occurring over a long period of time.

8.24The partial defence of loss of control, as enacted in the United Kingdom, is a general defence. Confining such a defence to victims of family violence would be a challenging exercise of legislative drafting.

Diminished responsibilityTop

8.25Diminished responsibility is a well-established defence in a number of jurisdictions, identified at paragraph 6.68 above. The principal requirement for the defence is that a person has a “substantial impairment” from being able to act in the manner as a person without such impairment would act.

8.26The Law Commission recommended against introduction of the defence in 2001. It considered diminished responsibility was a “difficult concept to define clearly”455 and may be inapt for victims of family violence since it seeks “the reason for the defendant’s actions in her mental abnormality, rather than in the desperation of her circumstances”.456 As noted at paragraph 6.69, diminished responsibility was considered, but not recommended, by the Victorian Law Reform Commission for similar reasons.

8.27We note that a partial defence of diminished responsibility has particular conceptual problems, especially if it is confined to the circumstances of family violence. Such a defence is regarded as more appropriate if it has general application. In any event, a partial defence of diminished responsibility may be an unhelpful lens through which to assess the actions of victims of family violence who kill their abusers. It implies that victims of family violence have lost their ability to make reasonable judgements about their situation.

Killing for preservation in an abusive domestic relationshipTop

8.28Another option is a specific partial defence for victims of family violence who commit homicide. As discussed in Chapter 6, Queensland has established a specific partial defence in respect of “killing for preservation in an abusive domestic relationship”. The partial defence requires that the deceased has committed acts of serious domestic violence in the course of an abusive domestic relationship, that the person believed it was necessary to kill for the person’s preservation from death or grievous bodily harm and that the person had reasonable grounds for that belief.457
8.29The specific defence was introduced in response to a recommendation from the Queensland Law Reform Commission (QLRC).458 In essence, the QLRC identified problems with victims of family violence relying on provocation and recommended a separate tailored defence rather than amending provocation. However, as we discussed at paragraph 6.56, the circumstances that gave rise to the QLRC’s recommendation for a specific partial defence were unique to Queensland and arguably do not apply in New Zealand. In particular, Queensland has a substantially narrower version of self-defence that requires an unlawful and unprovoked assault. In New Zealand, it could be argued that, if the defendant satisfied the requirements identified in paragraph 8.26 above, they would have a legitimate case for self-defence (and complete acquittal) under section 48. Further, Queensland, unlike New Zealand, retains a mandatory life sentence for murder. The QLRC’s reference was also limited to considering provocation rather than the law of homicide (and self-defence) as a whole.
8.30Nonetheless, there could be room for a partial defence of “excusable self-preservation” in New Zealand, although the elements of such a defence would need to be carefully crafted. It would be intended to capture cases where the defendant is responding to a long history of family violence, and those circumstances mean they should not be fully culpable for the offence. Such a specific partial defence has some support from New Zealand commentators.459 In 2001 the Law Commission considered a partial defence that would apply to:460
. . . any woman causing the death of a person:
(a) with whom she has, or had, a familial or intimate relationship; and
(b) who has subjected her to racial, sexual and/or physical abuse and intimidation to the extent that she:
(i) honestly believes there is no protection nor safety from the abuse; and
(ii) is convinced the killing is necessary for her self preservation.
8.31However, the majority of submitters in 2001 did not favour a specific defence, and the Commission concluded sentencing discretion for murder was preferable.461
445Law Commission, above n 8, at [24].
446See: R v Erstich, above n 20; R v Suluape, above n 165; R v King, above n 273; R v Neale, above n 127; R v Reti (2009) 271 NZCA.
447Law Commission, above n 8, at [183].
448Crimes Act 1900 (NSW), s 421.
449Criminal Law Consolidation Act 1935 (SA), s 15(2).
450Criminal Code Act Compilation Act 1913 (WA), s 248(3).
451Law Commission, above n 7, at [67].
452At [68].
453Coroners and Justice Act 2009 (UK), s 54.
454Section 55(3).
455Law Commission, above n 7, at 47.
456At 47.
457Criminal Code 1899 (Qld), s 304B.
458Queensland Law Reform Commission, above n 182.
459Simester and Brookbanks, above n 129, at 525–526.
460Law Commission, above n 7, at 27.
461At 30.