Inside Parliament, MPs focused on the tensions between religious freedom and human rights, and whether a referendum was required before the Marriage Act was changed.
New Zealand First leader Winston Peters' attempt to delay a law change until a public referendum was ruled out of order because Parliament had already voted against it two weeks ago.
Amendments tabled by several MPs to give all celebrants the right to choose who they would marry were also voted down.
MPs have long tussled over who would be able to refuse to marry couples if the law was changed, with the bill's sponsor arguing that all celebrants were already protected in the Marriage Act.
After concerns were expressed by churches and the New Zealand Law Society, an amendment was made to the legislation to explicitly protect religious ministers and organisational celebrants from breaching discrimination laws if they did not want to marry a couple on religious grounds.
Independent celebrants who conducted nearly half of the 22,000 marriages in New Zealand were not covered by this amendment, and some MPs felt it should be made clear that they too should be able to choose whom they married.
Labour MP Su'a William Sio drafted an amendment to allow this, but it was voted against by 82 votes to 22.
Labour MP Ruth Dyson, who chaired the committee considering the bill, said the amendment extended the freedom to discriminate too far.
"Protecting human rights was one [issue] that we found particularly difficult to resolve and I think that we have got it absolutely right," she said.
Green MP Kevin Hague went further, saying that while the fears behind the proposed amendments were sincere, the concerns were "imaginary" or had already been dealt with in the bill.
Despite assurances from the Human Rights Commission that it would not uphold complaints against celebrants, some legal experts felt that complaints might have to be decided by the courts.
The bill would return to Parliament for its final hurdle next month.
22,000 per year
23 per cent conducted by registrar
32 per cent conducted by church or organisational celebrant
45 per cent conducted by independent marriage celebrant.
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