The defence of provocation "effectively rewards a lack of self-control" and should be scrapped, Justice Minister Simon Power said today.

Debate has raged over the defence during the trial of Otago University tutor Clayton Weatherston, 33, who was yesterday found guilty of murdering his girlfriend Sophie Elliott.

He had pleaded guilty to manslaughter but denied murder on the basis of provocation. He had stabbed Ms Elliott 216 times.

Outside the Christchurch courthouse yesterday, Ms Elliott's father, Gil Elliott, said the provocation defence should no longer be an option.

"We don't like it. It is completely unnecessary and we hope it will be withdrawn now from the statute book."

Lesley Elliott, Sophie's mother, agreed it should be dropped: "If that's a legacy that Sophie leaves behind, that's good."

Women's Refuge and the Sensible Sentencing Trust also called for the defence to be removed.

Today, Mr Power said in a speech to the Institute of Policy Studies he did not believe the defence of provocation had any place in law.

"It wrongly enables defendants to besmirch the character of victims, and effectively rewards a lack of self-control," he said.

"The partial defence of provocation will be the subject of reform."

Work was also under way on domestic violence legislation aimed at improving the responsiveness of the Family Court and enhancing the protection of children.

The legislation would:

* Clarify when children remained covered by a protection order;
* prevent the wrongful removal of children from New Zealand;
* support programme attendance;
* clarify the treatment of temporary orders; and
* better align the Domestic Violence Act 1995 and the Care of Children Act 2004.

Mr Power has also asked the Law Commission to look at how sexual violence was dealt with.

He is considering reforms such as introducing a positive definition of consent; someone would have to say "yes" rather than a defendant being able to argue they did not say "no".

Evidence about the complainant's previous sexual relationships would be inadmissible without the judge's prior agreement, and the court would have to consider any steps the defendant took to ascertain consent.

"I have also asked the Law Commission to look at alternatives for dealing with sexual violence cases before the courts, with specific direction to investigate inquisitorial models".

"This is a debate we need to have if we want to improve on the reporting rate of 9-12 per cent for sexual violence offences," he said.

Prime Minister John Key earlier flagged Mr Power's speech saying there would be "a lot of support around the Cabinet table for the moves that Simon Power has attempted to lead".

Defence lawyer Peter Williams, QC, said the Government's move was a knee-jerk reaction and "very dangerous".

"It's like playing around with the onus of proof or playing around with self-defence or any of the other basic concepts of criminal law," Mr Williams said.

He said the Government should be consulting with those involved in the criminal justice system.

However, asked earlier if Mr Power's move was a knee-jerk response, Mr Key said it was not.

"This is an issue that the Minister has been considering for quite some time and forms part of the package of reform in the justice area," Mr Key said.

He said the Government would look at both sides of the argument.

"If anything the case recently, with Clayton Weatherston, highlighted how this provocation can be misused," Mr Key said.

University of Auckland professor of law Warren Brookbanks said abolishing the provocation defence would not make any difference to how murder trials are run.

"Trial lawyers are nothing if not inventive. The abolition of provocation will simply lead to a change of focus in homicide trials where the defence of provocation would otherwise have been run."

He said the abolition of provocation would not make the "ugly facts of homicide trials suddenly disappear" and would only lead to different ways of witnesses being victimised again.

"That may be the price we have to pay for removing one of a very small number of defences specifically available where the offence charged is murder," Prof Brookbanks said.

The Law Commission has previously called for the defence of provocation to be scrapped.

"We believe that it will be preferable for provocation to be dealt with by judges solely as a sentencing issue," a statement from the Commission in 2007 said.

In the commission's summary, Sir Geoffrey Palmer said the provocation defence had been used "all too frequently" in killings that had come after a homosexual advance.

He also noted that 12 of the 16 Crown solicitors supported a repeal while the defence bar was opposed because "partial defences perform a useful and necessary function in the criminal justice system".

View the Law Commission's review of the partial defence of provocation here.

However, the Law Society supports the retention of the provocation defence.

Criminal law committee convener Jonathan Krebs said the committee recognised that provocation was problematic, it was not easy to explain, and it was not easy for the jury to understand.

"However, it should be retained until there was some alternative," Mr Krebs told the NZPA in 2007.

After Clayton Weatherston's conviction yesterday, Women's Refuge said the provocation defence was based on "absolutely archaic notions about violence".

"Because of the way the defence was run, this trial became a perverse opportunity for a killer to continue to persecute his victim and her family after her death," chief executive Heather Henare said.

"The provocation defence is based on absolutely archaic notions about violence. Once upon a time, society accepted that an affront to male privilege or dignity was a reasonable excuse to fly into a homicidal rage.

"This trial turned justice inside out. The killer became the victim and Sophie Elliott was portrayed to us all as he chose to describe her. Unfortunately for Clayton Weatherston, the jury didn't buy it and nor did the hundreds of thousands of New Zealanders who watched him giggling on television."

Ms Henare said she was "horrified" to hear Ms Elliott's mother described as an unreliable witness and expressed sympathy for her family's ordeal.

"I believe there will be a strong and justifiably angry reaction to the way this trial proceeded. New Zealanders hearing so many of the details and seeing Weatherston taking the stand will have been absolutely dumbfounded that this remorseless killer has had a platform for his justifications and excuses - televised and thoroughly reported by the media."

* Provocation defence - what it means:

The defence is covered under section 169 of the Crimes Act 1961.

The provocation defence allows for a killing that would otherwise be classed as murder to be downgraded to manslaughter if it can be proven that the person who caused the death was provoked.

The provocation must have some relation to a characteristic of the offender.

It must cause the offender to lose the power of self-control of an ordinary person and have induced the offender to kill.

What the blogsphere is saying

"In recent years more and more I see the provocation defence being used to slander the dead, and especially used for "homosexual panic" claims. One case had a the accused get manslaughter only with this defence despite the fact he was a male callboy!

"If unwanted sexual advances was legitimate provocation to kill someone, the population would be greatly reduced."

Stephen Franks:

Eliminating the defence of provocation is not the answer. It can be a legitimate excuse. There may be times when provocation does reduce the moral culpability of murder to manslaughter, when the murderous reaction is what any normal person could feel driven to. But it should not be allowed to work if it only works when coupled with "I was drunk" or " I was a nut case" "he was gay".

Say hello to my little friend blog:

"This kind of overreaction is common in New Zealand, but quite misguided. The line of thinking is that since Calyton Weatherston's lawyer tried to use it, and since Clayton Weather was clearly not provoked, the defence of provocation should be repealed. What nonsense!"

Red Alert (Labour Party blog)

Lianne Dalziel

"This has raised serious concerns that there is a real risk that an underlying prejudice or phobia could sway a jury into letting someone literally get away with murder. It has been interesting to hear all the arguments that are now able to be focused on the defence itself."

Not PC blog

"Our right to life gives us our right to self defence - what it doesn't do however is give us a right to retaliate in cold blood, or even highly-charged blood."

Imperator Fish

"Inevitably, a defence of provocation requires the defendant to impugn the character or good name of the victim. But arguably in the Weatherston trial things were pushed too far."

- With NZPA