The Netherlands legislated for same-sex marriage in 2001 and 23 other countries followed.  In 2004, however, the Liberal-National Party government amended Australian legislation to define marriage as "the union of a man and a woman to exclusion of all others”. 

Australian Marriage Equality, and various other groups, subsequently campaigned to legalise same-sex marriage.  Numerous polls indicated most Australians supported marriage equality and support was strongest in younger age groups. 

With pressure to act, but major resistance within its ranks, the Liberal-National Party government devised a non-binding, voluntary ‘survey’ of Australians’ support for marriage equality, conducted in September and October 2017. 

The YES! Rallies for Marriage Equality held in Sydney on September 10 and October 21 were part of a national campaign during the survey period.