No partial defence to murder

33Partial defences are controversial. Supporters argue that they promote “fair labelling”, enhance the role of the jury, and have the potential to positively impact on charging practices and sentencing. Detractors emphasise that partial defences are anomalous in the criminal law, tend to go hand-in-hand with mandatory sentencing for murder (which has been abolished in New Zealand), and can have undesirable or perverse effects. We review these general arguments and explore the possible formulations for a partial defence targeted at victims of family violence. We look at three broad categories of partial defences, although there is some overlap:

34The most common formulation of a “defence-based” partial defence is “excessive self-defence”, which was recommended by both the Victorian Law Reform Commission and the Law Reform Commission of Western Australia. Excessive self-defence has, however, since been disavowed in Victoria and other Australian states, and by courts in the United Kingdom, New Zealand and Canada.

35The second broad category of partial defences is based around provocation, which is the only partial defence that has previously been part of the law in both New Zealand and comparable jurisdictions. We found no empirical evidence from our case review to conclude that repeal of provocation in New Zealand has in practice adversely affected the position of victims of family violence who kill their abusers.

36Provocation has been subject to some notable recent reform in England and Wales, with the remodelled “loss of control” formulation. Loss of control focuses on a “qualifying trigger”, which may include the defendant’s fear of serious violence. Inclusion of fear of serious violence as a qualifying trigger was intended to better accommodate the position of victims of family violence who kill their abusers. Its effectiveness in this regard has, however, been subject to considerable debate.

37Those who favour a provocation-based partial defence consider that it could appropriately accommodate conduct that was responsive to abuse, but not defensive. Others are opposed to reintroduction of any provocation-based defence in New Zealand.

38The third broad category of partial defences focuses on a defendant’s capacity, and looks into the mind of the defendant to see if he or she should be judged by some lower standard than the ordinary person. These defences do not share provocation’s objective requirement (that the provocation have a similar effect on a similar person), and are intended to fill the gap where a person would not be able to plead insanity.

39A significant problem with diminished capacity defences is that they tend to entrench misleading stereotypes of primary victims of family violence – who are mainly women. Further, in New Zealand, the Sentencing Act 2002 already provides scope to take into account the diminished intellectual capacity of the defendant as a mitigating factor in sentencing.

40Based primarily on the experiences of comparable jurisdictions, we conclude that none of these options for a partial defence would be appropriate for victims of family violence in New Zealand.

41Finally, we consider the merits of a new type of partial defence, which does not fit discretely into the above three broader categories, but is “trauma-based”. This would be a bespoke defence tailored to victims of family violence who kill their abusers. We conclude that introducing a context or victim-specific defence would be inconsistent with New Zealand criminal law principles and legislation unless there is a specific and compelling rationale.17 For the reasons set out in Part 2 of the Report, we are satisfied there is such a rationale in connection with the application of self-defence to victims of family violence who kill their abusers, which warrants our recommended clarification to section 48. We did not, however, find this test to be met for a new partial defence or specific homicide offence in this context.

42Ultimately we recommend against the introduction of any new partial defence or separate homicide offence in New Zealand. We consider the case is not made out for such an approach and that any reform in this area would carry an unacceptable risk of unintended consequences.


17We adopt the same conclusions as the Law Commission did in Review of Part 8 of the Crimes Act 1961: Crimes Against the Person (NZLC R111, 2009) at 30–31. See also Law Commission Strangulation: The Case for a New Offence (NZLC R138, 2015) at [1.17].