The partial defence of provocation, which can be used to reduce murder to manslaughter, has been abolished.
Parliament passed the repeal bill tonight by 116 votes to five, with only the ACT Party opposing it.
Justice Minister Simon Power introduced the Crimes (Provocation Repeal) Amendment Bill in August after the Law Commission had twice recommended abolition.
He said at the time the Government considered the law was fundamentally flawed.
"It effectively provides a defence for lashing out in anger, not just any anger but violent, homicidal rage," Mr Power said.
"It rewards lack of self-control by enabling an intentional killing to be categorised as something other than murder."
The partial defence of provocation was under intense debate after Otago University tutor Clayton Weatherston argued he was provoked into stabbing girlfriend Sophie Elliott 216 times.
Weatherston pleaded guilty to manslaughter but the jury found him guilty of murder.
Labour, the Greens and the Maori Party strongly supported the repeal bill and there were cries of "shame" when ACT MP David Garrett said his party opposed it.
Mr Garrett said the central point in the Weatherston case, which other parties had not recognised, was that the partial defence failed.
"Abolishing it suggests we don't trust juries," he said.
"This (repeal) shifts the argument of provocation from juries to judges, who can consider it in sentencing...it makes more sense to put our trust in juries."
