Same-sex marriage became legal in New Zealand on 19 August 2013. A bill for legalisation was passed by the New Zealand House of Representatives on 17 April 2013 by 77 votes to 44 and received royal assent on 19 April 2013. It entered into force four months after assent, to allow time for the Department of Internal Affairs to make the necessary changes for marriage licensing and related documentation. New Zealand became the first country in Oceania, the fourth in the Southern Hemisphere, and the fifteenth overall to allow same-sex couples to marry.
The Parliament of New Zealand can enact marriage laws only in regard to New Zealand proper and the Ross Dependency (Antarctica). The three other territories making up the Realm of New Zealand—the Cook Islands, Niue and Tokelau—do not perform or recognise same-sex marriage.
The case Quilter v Attorney-General had its origin in early 1996 when three female couples in long-term relationships were denied marriage licences by the Registrar-General because marriage under the common law was between one man and one woman. The case against the Government was taken to the High Court in May 1996. The applicants argued that the Marriage Act 1955 did not prohibit same-sex marriage and that under the New Zealand Bill of Rights Act 1990 and the New Zealand Human Rights Act 1993, discrimination on the basis of sexual orientation was prohibited.
Both parties agreed that at the time the Marriage Act 1955 was written in the 1950s, marriage according to the common law was between one man and one woman, which explains why the Act did not specifically outlaw same-sex marriage. The applicants argued, however, that under the Human Rights Act, which prohibits discrimination based on sexual orientation, and sections 6 (Interpretation consistent with Bill of Rights to be preferred) and 19 (Freedom from discrimination) of the Bill of Rights Act, New Zealand prohibits discrimination based on sexual orientation and, therefore, the applicants should be allowed to marry. The Government in response cited section 5 (Justified limitations) of the Bill of Rights Act, which allows rights and freedoms in the Bill of Rights to "be subject only to such reasonable limits prescribed by law as can be demonstrably justified in a free and democratic society". In its decision, the High Court sided with the Government and common law and reiterated that marriage is between one man and one woman.