The Law Commission wants to change laws affecting domestic abuse victims who kill their partners.

Victims of family violence who kill their abusers should be able to claim self-defence more easily, the Law Commission says.

The commission's report on family violence laws, requested by the Government, has recommended lowering the threshold for self-defence to help women who "have endured years of trauma and abuse".

In its report, the Law Commission said New Zealand had the highest reported rate of family violence in the developed world.

KIRK HARGREAVES / FAIRFAX NZ Justice Minister Amy Adams says the Law Commission's recommendation would be "a significant departure" from current laws.

The commission has recommended changing the law to state that self-defence can apply when a person is responding to family violence - even when the threat is not "imminent", as currently must be the case.

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Lead commissioner Dr Wayne Mapp said there were some "deeply-held myths" about family violence, such as that those being abused could simply walk away.

FAIRFAX NZ Family violence victims who kill their abusers are often defending themselves after "years of trauma and abuse", the Law Commission says.

"The reality is family violence in many cases is part of an ongoing, sustained, vicious pattern of violence that traps the person.

"That entrapment means she cannot leave, and that then means she ultimately, for fear of her life, or that of her children, sees no other way out but to defend herself with lethal force."

Mapp said New Zealand's self-defence laws were "out of step" with countries like the UK and Australia, and there was "ample evidence" that women convicted here of manslaughter or murder should have been acquitted for acting in self defence due to family violence.

He did not believe changing the law would lead to people using family violence as an excuse for premeditated murder, saying it would be up to juries to decide whether a self-defence claim was believable.

The law change could allow a woman to kill her sleeping partner and claim self-defence, if she made a "believable" case of family violence.

"Such a claim would only be successful if it existed in the context of a sustained long period of family violence, and if you didn't do that then, the next thing going to happen to you is that you were going to be killed instead."

'A TERRIBLE CONSEQUENCE OF FAMILY VIOLENCE'

Other recommendations in the report were:

* Allowing a broader range of evidence about family violence to support claims of self-defence.

* Ensuring "consistent consideration" of a history of family violence as a mitigating factor during sentencing.

* Continuing to educate judges, prosecutors and defence lawyers about family violence.

* Reviewing the "three strikes" law and how it affects victims of family violence.

Women's Refuge New Zealand chief executive Ange Jury said the self-defence proposal was "a good move forward", given what victims of family violence had to deal with.

"It's been likened to a form of terrorism, and I don't think that's going too far...unless you've actually been there, I don't think anyone can know what that feels like."

However, Jury said the most important recommendation was educating those in the justice system about the nature of family violence.

"Unless the people administering the law have a really good, sound understanding of what domestic violence is, what it looks like, what it does, it's not going to be administered properly anyway."

'WE HAVE TO BE INCREDIBLY CAREFUL'

Justice Minister Amy Adams said she welcomed the Law Commission's "comprehensive" report, which the Government had asked it to prioritise.

"A terrible consequence of family violence is that some victims are driven to killing their abusers - as a result of often years of abuse."

Adams said the Law Commission's proposals would be "a significant departure" from the current laws, and would need "careful thought and discussion".

"We have to be incredibly careful - letting someone off killing another human being is an incredibly serious thing to do."

The recommendations would be considered as part of the Government's work on family violence, she said.

VICTIMS WHO STRIKE BACK

The Law Commission has identified a number of New Zealand cases where victims of family violence who killed their abusers, including:

* Amanda Taitapanui: The 29-year-old was sentenced to 12 months of home detention in April for manslaughter after fatally stabbing her partner Mura Dean Tagatauli in the leg. A police summary about the killing said the couple had an "extensive family violence history".

* Dale Wickham: In 2010, the 62-year-old was sentenced to 12 months home detention for manslaughter after killing her husband John Wickham. Her lawyer said at trial Wickham had put up with years of abuse from her husband, who had made threats to kill her by hitting her with a brick and putting her body in the pool to cover it up.

* Gay Oakes: In 1995, Oakes received a life sentence for murder after poisoning her partner Doug Gardner and burying him in the garden of their Christchurch home. Oakes was furious at the abuse he meted out to her and their children, but a partial defence of provocation failed at her trial.