By Henry Cooke

David Seymour's End of Life Choice bill has passed its second reading 70-50 and is taking legal assisted dying one step closer to becoming law.

Labour and National MPs voted with their conscience on the issue, while Green and NZ First MPs all voted in support.

33 Labour MPs voted for the bill, including leader Jacinda Ardern, while 13 did not. 18 National MPs voted for the bill, while 37 - including leader Simon Bridges - did not.

The second legislative hurdle follows a first reading in late 2017, after which the bill went through a marathon 16-month select committee process, which it emerged from with almost no changes, to the frustration of Seymour who wants to change the bill himself.

The bill in its current form would allow someone with a terminal illness that is likely to kill them within six months, or a "grievous and irremediable medical condition", the option of requesting assisted dying.

But Seymour is keen to amend it to limit the option to only those who are terminally ill at the committee of the whole house stage ahead of its third and final reading.

This amendment will be necessary to keep the eight Green MPs onboard with the bill, which has faced a lot of backlash from the disabled community who fear it will be used to coerce the disabled into ending their lives.

Another amendment to provide for a referendum on the issue is required to keep the support of the entirety of the NZ First caucus.

Seymour lost 6 votes from the first reading but easily cleared the 61-vote line needed for a bill to pass. Between first and second reading nine MPs changed their votes from yes-to-no while three changed from no-to-yes. Several also retired.

In his speech moving the bill, Seymour asked the MPs to consider the small number of New Zealanders who are going through a painful end to their lives right now.

"Do we require them to suffer on behalf of the morality of others? Or do we give them the compassion of choice?" Seymour asked.

Several MPs discussed personal stories of painful deaths of those people close to them.

National's Amy Adams said her mother died in tremendous pain - not because of a lack of hospice care or drug access but because she didn't want to be highly medicated in her final hours.

Fellow National MP Agnes Loheni spoke strongly in opposition to the bill.

"We cannot risk one wrong death. This bill cannot guarantee that will not happen," Loheni said.

One MP changed her vote from a "no" at first reading to a "yes" at second - firebrand National MP Judith Collins.

Collins told Stuff she had serious concerns about the safeguards in place but had talked to Seymour and was confident that he wanted similar safeguards. She would reassess her vote at third reading based on whether those safeguards had been put in place.

"These are real life situations for people. And I think people would like to think that if they were at all fearful of pain or distress or an ability to communicate then they would like to have some choices," Collins said.

She recounted the tale of her father who died with "massive amounts" of morphine in his system.

"I have always been opposed to euthanasia as of right on the basis that people like my dad got to, essentially, tell everybody when they wanted to go, and I thought that was available to everybody. It's not available to everybody. It's not available for people like my dad who happen to be in the wrong place at the wrong time and without a family saying, "You give my dad everything he needs." That's the shame of this," Collins said.

National MP Nick Smith spoke in strenuous opposition to the bill.

"The problem I have with this bill is it's out of step with a core part of our Kiwi culture, that respect for human life. In many parts of the world life's cheap. But here we go to extraordinary lengths to protect human life. It's actually not that New Zealanders are puritanical or deeply religious. It's actually a very down to earth, practical caring. It's why we've been a world leader in an area like Special Olympics and disability rights, in asserting that every life has value," Smith said.

"It's why we were one of the first countries in the world to get rid of the death penalty. We want to err on the side of life. The cold, calculating clauses in this bill allowing the termination of life of someone who's unwell or disabled contradicts those basic Kiwi values."

Speaking after the bill, Seymour said he was pleased with the margin, which was higher than he had expected, but that much work remained.

 "We are very pleased we got 70 votes but we have a lot of work to go before New Zelanders have this choice," Seymour said.

"This is a five stage process and we just got thought stage three and there are another two big stages to go."

The committee of the whole house stage could take months with fierce opponent Maggie Barry promising she has 120 proposed amendments at the ready.

After that stage the bill would go to its third and final reading before becoming law - unless instead it was sent to the public as a referendum.

Speaking after the bill passed Barry said many MPs had been "seduced by the idea that  they needed to vote it though to the third reading so that there would be a range of options that would be considered."

She believed up to 12 MPs were definitely against the bill but had voted it through second reading as to not stifle the debate.

"The idea that it should go to the third reading was something that would always have a lot of appeal," Barry said.

She promised "a very big fight" at the committee of the whole house stage but said she would have to see any amendments before making her mind up on how to vote for them.

The lobbying for and against the bill is likely to step up significantly in the coming months.

Former prime minister and conservative Christian Bill English has been very involved with the campaign against the bill, but opposition has also come from medical associations and lawyers.