Justice Minister Simon Power says the defence of provocation has no place in New Zealand's statute books and will seek approval from the Cabinet within the next three weeks to scrap it from murder cases.
Mr Power told the Institute of Policy Studies at Victoria University on Thursday that the partial defence wrongly enables defendants to besmirch the character of victims and effectively rewards a lack of self-control.
Former university tutor Clayton Weatherston, who was found guilty on Wednesday of murdering Sophie Elliott, had sought to convince the jury at the High Court in Christchurch that he was provoked so he would be found guilty of manslaughter instead.
Weatherston, 33, had admitted killing Miss Elliott, his ex-girlfriend, whom he cut or stabbed 216 times in her Dunedin home.
Mr Power on Thursday refused to be drawn on the Weatherston case. However, he says there are other aspects of the law that can deal with self-defence or unjust circumstances in sentencing.
Legislation to remove the defence of provocation would get wide support in Parliament as main opposition party Labour supports scrapping it.
Mr Power told Checkpoint on Thursday the defence of provocation has passed its use-by date and is confident he will get support from the Cabinet.
The minister is also signalling big changes in sexual abuse trials.
They include whether there should be a positive definition of consent and for the court to consider whether the defendant tried to establish if consent had been given.
Elliott family want provocation defence scrapped
The parents of Sophie Elliott want to see the defence of provocation dropped from New Zealand law so that no other parents have to sit through a trial as they have done.
Gilbert and Lesley Elliott say it was unfair on their daughter that Weatherston used the defence of provocation, which gave him the opportunity to sully her reputation, and it is time for a law change to remove provocation as a defence.
Lesley Elliot told Morning Report on Thursday that she could not see circumstances in which provocation was a valid defence to murder.
"We thought about it a lot over the last few weeks, and probably there's not very many murders where provocation is justified. And in our society it's never justified. 'Thou shalt not kill' ... that's the bottom line," she said.
Mrs Elliott said she felt like her daughter was on trial, because of the use of provocation as a defence.
The issue of provocation also arose during the recent conviction of Ferdinand Ambach for manslaughter after it was argued his victim had made sexual advances to him.
Gay rights advocate Neville Creighton says only self-defence could justify causing death. He would support the replacement of the defence of provocation with something along the lines of the American system of degrees of murder.
Victim Support chief executive Tony Paine says the provocation defence sends an "unfortunate signal", since no anger can justify murderous violence.
Law Commission report
In 2007, a report by the Law Commission advocated that the defence of provocation be removed.
The commission says allowing accused murderers to use the defence of provocation has no place in the 21st century.
Commission deputy president Warren Young says in trials using the defence of provocation it can often appear that the victim's behaviour, rather than their alleged killer, is on trial.
Dr Young says that greatly increases the trauma for the victim's family.
Auckland defence lawyer Barry Hart says defendants often try to convince juries they are guilty of manslaughter instead because of a lack of flexibility in the court system.
He says provocation should be kept as a defence or replaced by one of diminished responsibility or a system of degrees of murder.
Labour's justice spokesperson Lianne Dalziel has a members' bill in the ballot to scrap the defence of provocation in murder trials would allow judges to adjust sentencing to take into account the circumstances leading up to a killing.
