Clayton Weatherston: 216 stabs manslaughter?

I don't like to comment on court matters, as I think that we, the public, can't really judge. We don't hear all the evidence; only what the media choose to pass on. Even the court may not know what really happened. But in this case, the crime isn't denied; only the charge.

Last year, Clayton Weatherston killed his ex-girlfriend, Sophie Elliot, by stabbing her 216 times. He never denied that he killed her. But he's claiming it's manslaughter rather than murder because she provoked him.

So my argument here is purely as a question of law. The Crown are arguing it was premeditated murder (he took a kitchen knife with him to visit her); the defence are saying it wasn't murder because he was provoked (Sophie had allegedly cheated on him while they were dating, and allegedly attacked him with scissors).

Isn't that still murder?

My understanding was that there were basically three levels of killing.

Manslaughter: "Unlawful killings without malice or intent are considered manslaughter", e.g. someone driving a car without reckless disregard hits a child who runs out in front of the car.
Second degree murder: "Any intentional, unlawful killing done without justification or excuse" (common law), i.e. intent to kill (not necessarily premeditated) or actions with "reckless disregard" for human life. I think these are the "crimes of passion" — e.g. finding your wife and your best friend in bed together, or losing control of your emotions when confronting an unfaithful ex-girlfriend.
First degree murder: The "unlawful killing of a human being with malice aforethought" (common law). Basically, second degree murder only worse. These are generally the premeditated murders, e.g. stealing your dad's gun to lie in wait and shoot the school bully, or taking a kitchen knife to visit your unfaithful ex-girlfriend to kill her.

So to me, the verdict seems clear. CW is claiming manslaughter. Manslaughter is an "unlawful killing without malice or intent". Was there malice? Yes. Was there intent? After 216 stabs, I'm gonna say so.

To me, the only question is what degree of murder he should be convicted with. But I'm aware my knowledge of New Zealand law is scanty. I've also heard that in most parts of Australia, murder can be downgraded to manslaughter if there has been provocation.

Has this ever been a part of NZ law, or is that just those crazy Australians? Is there anything in NZ law that acknowledges provocation as a just reason to downgrade a charge of murder to manslaughter?

To me, manslaughter says accidental. Even CW admits it wasn't accidental.

But would NZ law really allow provocation to be used as an excuse?

Update: The verdict.