The Law Society says the defence of provocation should be kept until something better is developed to replace it.
But gay rights advocates say the defence is legalised gay bashing and should have been ditched years ago.
Parliament's justice and electoral select committee is considering a government bill to abolish the partial defence of provocation.
Justice Minister Simon Power said earlier the change was on the cards before the controversial case of Otago University tutor Clayton Weatherston who argued he was provoked into stabbing girlfriend Sophie Elliott 216 times.
Weatherston pleaded guilty to manslaughter but the jury found him guilty of murder.
The Law Commission has twice recommended abolition, first in 2001 and again in 2007.
In a written submission on the bill, New Zealand Law Society president John Marshall QC said the commission's previous recommendation was made when the Labour government was planning to introduce a Sentencing Council and sentencing guidelines, but they were no longer going ahead.
The society's criminal law committee believed the defence should be retained "pending the development of other forms of defence".
Among its concerns were that it was not always appropriate that a provoked killer be labelled a murderer and that it should not just be up to a judge to determine where there was enough provocation to reduce the charge to manslaughter. It also said sentencing might not take into account lesser culpability.
"If the partial defence were to be abolished, juries might convict on the alternative charge of manslaughter based on their sympathy for the defendant rather than on rational grounds," it said, citing another worry.
Mr Marshall said forms of defence could include, for example, diminished responsibility or degrees of murder.
Rainbow Wellington spokesman Tony Simpson was keen to see the defence dropped immediately.
While seldom successful, the defence had been used to assassinate the character of gay victims over the years and it was hard to accept when it resulted in an offender escaping penalty.
In July, Ferdinand Ambach was found guilty of manslaughter rather than murder after killing 69-year-old gay man Ronald Brown.
Mr Brown was beaten with a banjo before the instrument's neck was rammed down his throat. It was alleged he made sexual advances to Mr Brown.
Mr Simpson said there had been calls for change since Charles Aberhart, a gay man from Blenheim, was kicked to death in Hagley Park in 1964 by six youths aged between 15 and 17. They were found not guilty, despite evidence that they had gone to the park for a "spot of queer bashing" after alleging Mr Aberhart had provoked them by making a sexual advance.
It appeared the Government was willing to act when the case was about a man and a woman when the defence was unsuccessful, despite years of agitation for change after the defence was successful in cases against gay victims, Mr Simpson said.
"It's very hard to escape the question from our point of view that while it was just a couple of gays getting whacked nobody was all that concerned, but when a pretty young girl was involved it was somehow different."
The existing law as a "homophobic hangover," he said.
Kiri Hannifin from the National Collective of Independent Women's Refuges said her organisation supported the repeal.
"The law has done nothing to protect victims of violence, indeed perversely it's often used against them, and the Weatherston case is a recent example of that."
However, she was concerned the law did not properly cater for victims of domestic violence who killed their abusive partners.
"We're concerned that if provocation is abolished and we don't sort out self defence and sentencing isn't appropriately addressed, there is a huge gap in our legal framework for women who kill their husbands or partners because they themselves believe that if they don't they or their children will be killed."
