<P> The history of same - sex marriage in Australia includes its express prohibition by the Howard Government in 2004 and its eventual legalisation by the Parliament in December 2017 . Although a same - sex marriage law was passed by the Australian Capital Territory in 2013, it was struck down by the High Court on the basis of inconsistency with federal law . The Court's decision closed the possibility of concurrent state or territory laws that would allow same - sex marriage where federal law did not . A law legalising same - sex marriage passed the Parliament on 7 December 2017 and received royal assent the following day . </P> <P> Between September 2004 and October 2017, there were 22 unsuccessful attempts in the Federal Parliament to legalise or recognise same - sex marriage under federal law . Former Prime Minister Malcolm Turnbull supported same - sex marriage during his time in office when same - sex marriage was legalised by the Parliament . The Turnbull Government went to the 2016 federal election with a policy to put the issue of same - sex marriage to a plebiscite, and was narrowly re-elected, though the legislation to establish the plebiscite was rejected by the Australian Senate in November 2016 . </P>

When did marriage equality became legal in australia