The Law Commission is suggesting a partial defence to murder for victims of family violence.
In reviewing the law, the commission said New Zealand was out of step with other countries in how the justice system responded to victims who killed their abuser.
Lead commissioner Wayne Mapp said the law of self-defence was too rigid and did not take into account ongoing family violence, while the charge of murder could be unfair.
The new defence, which would be similar to manslaughter, would apply to someone who had been deeply traumatised by violence over a long period of time, he said.
"The typical victim has suffered extreme violence over a long period of time - regular, severe beatings, violent sexual assaults - typically, the victim is deeply traumatised by what's happened," he said.
He cited the case of Napier woman Jacqueline Wihongi who, in 2010, was found guilty of murdering her partner, but jailed for only eight years.
The Court of Appeal later increased her sentence by four years, but said it wouldn't imprison her for life because of the mental impairment she suffered through the violence.
"These victims are usually charged with murder," he said.
"Homicide is one of the most important areas of the criminal law and it may not adequately recognise the position of victims of family violence."
The commission has asked the public for feedback and will deliver its final report in March.