The Labour Party is vowing to fight to abolish the defence of provocation in murder trials.
Labour's Associate Justice spokesperson Charles Chauvel has drafted a Member's Bill proposing to abolish the defence, which Labour's Justice spokesperson, Lianne Dalziel will sponsor.
Mr Chauvel says New Zealand is one of a handful of countries which allow such a defence.
He says if a killer experiences extreme violence or rage, the defence of provocation can mean a jury may be convinced to reduce a charge of murder to one of manslaughter.
Gay rights advocate Neville Creighton says the defence of provocation is antiquated and needs to be abolished. He says it has often been used because a homosexual advance was made.
On Thursday, a jury found Ferdinand Ambach, 30, not guilty of murder, but guilty of the manslaughter of Auckland man Ronald Brown, 69. Mr Ambach's lawyer argued he was provoked after Mr Brown made sexual advances towards him.