The proposed law to ban conversion practices has passed its second reading in Parliament on Tuesday evening.
About 25 MPs were in the House due to Covid-19 rules.
Labour, Green Party, ACT, and te Pāti Māori and 26 National MPs voted in favour of the bill. Seven National MPs voted against.
Labour's Shanan Halbert said MPs had a duty of care, and banning conversion practices was "one of those issues that how we vote will be remembered in years to come".
He said it allowed for "safe and open discussions", while also preventing the harm conversion practices caused and providing an avenue for redress for those impacted.
He said it had "no place in modern Aotearoa New Zealand".
"Sexuality, gender expression, and gender identity are not political issues – they are issues of humanity. It is confusing to me why such basic human rights are even up for debate in this house."
Labour's Ginny Andersen, the chair of the Justice Committee which heard the public submitters, said during the process at times she felt "close to tears" and "intense anger".
There were 107,000 public submissions on the proposed law – breaking the New Zealand record for the highest ever received. The select committee found 38,900 had unique content (not a copied template).
Andersen said 69 per cent were in favour of the bill, while 30 per cent were against.
National's Simon O'Connor said he voted against the bill at first reading as he thought it was problematic, he said it was now "argumentatively more problematic".
"It's not about dialogue it's about stopping speech. It's firmly in the area of free speech."
He said if the bill was to ban conversion therapy, then he would have supported it.
But, he said it went "so much further than that".
O'Connor said he had "lesbian and gay friends" who were concerned about the bill.
"If this was [a] narrow and well-defined bill, we'd be there in spades," he said.
Faafoi said: "It would help if you read it."
O'Connor maintained he had read it.
He asked if it could encourage gender-confirming behaviours.
He also asked if would capture "biological women who want to use terms biological terms like she or her?"
"Maybe it does, I don’t know… I just want a clear definition".
Some Labour MPs began laughing and shaking their heads.
He said there was an on-the-line "arrogance here which ultimately free speech is built on respect".
"Free speech is harmful, it is not safe and sometimes not respectful. That's the nature of it and that's how for 6000 years of recorded history humanity moved forward."
Labour's Vanushi Walters said the idea that free speech was under attack "is politics".
"I understand why, but it's too easy to frame it as this," Walters said.
"Free speech has never been absolute," she said, giving examples of defamation laws, perjury, false advertising, obscenity, solicitation of a crime, and the Harmful Digital Communication Act.
Green MP Elizabeth Kerekere said many of the submitters who had suffered harm after undergoing conversion practices had it done by "trusted people".
"To all of the people experiencing this right now, this is a stake in the ground, it is not acceptable and we will be stopping it."
National's Paul Goldsmith said he intended to support the bill at second reading, but would be introducing proposed changes at the next stage.
He said the bill was not just about "praying the gay away" and was broader about gender identity.
ACT's Nicole McKee said finding balance was hard as many people during the select committee process said it went too far and others said it did not go far enough.
She said they wanted to find the balance of "what is harmful and the freedom of speech and the freedom of thought".
McKee said ACT would be submitting proposed changes to make conversations with parents exempt and for a three-year initial review after the law was enacted, followed by a five-yearly review.
She said the party would continue to support the bill in its second reading as "we believe everyone has the right to have the freedom to choose about how they are and how they conduct themselves".
Te Pāti Māori co-leaders Rawiri Waititi and Debbie Ngarewa-Packer voted in favour of the bill, with their party tweeting, "this cruel practice is a direct attack on whakapapa and has no place in Aotearoa".
"Takatāpui are whānau. No ifs, no buts, no maybes. End of story."
Labour's Arena Williams said the intent of the law was "not about using the wrong pronouns".
"This is about [the] harm done to people, predominantly young people, predominantly people not used to having their identity affirmed in the first place."
National MPs could vote how they wanted, rather than voting along party lines.
National's Mark Mitchell said he supported the bill, but wanted assurance a parent having a conversation with their child would not be captured in the bill. Matt Doocey also spoke in support of the bill, acknowledging the party's youth wing, the Young Nats, for their advocacy of the bill.
The first reading of the proposed law to ban conversion therapy passed in August.
If passed into law, it could see someone imprisoned for up to three years in jail for performing conversion therapy on someone under 18 and up to five years where it has caused serious harm, irrespective of age. The Attorney-General needed to give consent for those prosecutions.
Labour promised in 2020 to ban conversion practices.