Kiwi MPs voted 69 to 51 on Wednesday night to pass the End of Life Choice bill, ending the issue's four-year journey through the Parliament but failing to resolve it.
The bill appeared likely to pass in October, when amendments forced its proponents to swing behind a referendum rather than legalise it outright.
But undecided members were lobbied by both sides until the very last hours, when almost a quarter of MPs gave speeches, often passionate and personal, during a marathon debate.
Many addressed their own faith, ethnicities and experiences with death.
Labour MP Willie Jackson, one of the few not to reveal his hand, finally declared himself a supporter with a touching address centred on his mother's deteriorating health.
"My mother changed dramatically from the passionate, strong Maori leader she was," he said.
"Last night I spoke with three of the most high-profile Maori leaders in this country.
"They all said they were tired of hearing that this was against our culture [tikanga]. Tikanga evolves and there is no one tikanga.