Moves to push for a law change allowing battered wives who kill their husbands in cold blood to plead self-defence are being considered by a government committee.

The Family Violence Deaths Review Committee says New Zealand is out of step with other countries in not offering at least a partial defence for women who kill their husbands after years of abuse.

The defence can be used when the killing is an immedite retaliation but not when the killing is premeditated.

The committee initially planned to recommend a law change, but has stepped back from that while it continues discussing the proposal.

The government body which sanctions the committee, the Health Quality and Safety Commission, will now workshop the proposal before making any formal suggestions.

A final draft of a report by the committee contained an extensive section suggesting the change but it was omitted in the public version.

Committee chair Julia Tolmie, an Auckland University professor, said she could not comment on behalf of the commission regarding the proposals.

Justice Minister Judith Collins' office said it would be "premature" to comment on any potential law change.

The original suggestion was to introduce a partial self-defence for family violence victims who kill, but not during an immediate assault, and modifying the self-defence test so they can use it.

It could also aid children responding to severe abuse of themselves or other family members.

It would partly be in response to the decision to remove the partial defence of provocation after the public outcry following convicted murderer Clayton Weatherston's failed attempt to use it as a defence in his 2009 trial for killing Sophie Elliott.

Removing that defence means it also can't be used by victims of domestic violence who kill abusive partners.

Family violence researchers say women who kill in cold blood cannot take the option of leaving a violent relationship because of mental health issues and the increased risk of violence after separation.

One study comparing murder conviction rates of battered spouses in New Zealand, Canada and Australia found New Zealand had a much higher rate.

England, Canada and most Australian states offer some defence for battered spouses, but judges in New Zealand have interpreted self-defence as a reaction to immediate threat.

For example, in 2010, Queensland woman Susan Falls was acquitted of murder on self-defence grounds after crushing sleeping pills in her husband's dinner of chilli prawns, shooting him while he slept and disposing of the body.

The court heard she had suffered years of horrific abuse.

New Zealand has interpreted self-defence as a response to an "imminent" threat, such as retaliating during a fight. In 2001, the New Zealand Law Commission recommended "imminent" be replaced with "inevitable".

In one 1998 case in Wellington, a Tuvalan immigrant who spoke no English received a two-year sentence for manslaughter by provocation after feeling trapped in an abusive relationship in a tight Wellington community of just 12 families.

Such laws have also been fiercely debated in England, with the cause celebre being Sara Thornton, jailed for life in 1990 for the knife murder of her husband, who she said was a violent alcoholic.

After a public campaign, Thornton won a re-trial and had her conviction reduced to manslaughter in 1996.