Malcolm Turnbull has introduced the Plebiscite (Same-Sex Marriage) Bill 2016 into the federal Parliament. The bill has been overshadowed by the debate over whether a plebiscite is desirable in the first place. Unfortunately for the Prime Minister, his bill strengthens the case of those who reject the national vote. It is flawed in key respects, and could be challenged in the High Court.

The plebiscite bill proposes that Australians be asked a simple question: "Should the law be changed to allow same-sex couples to marry?" This is the wrong question. It fails to capture the full extent of how the marriage act would be changed.

Many bills have been introduced into the federal Parliament to bring about same-sex marriage. These typically extend marriage rights not only to same-sex couples, but also to intersex people. The wider change is needed because same-sex marriage does not necessarily encompass people unable to identify as being either male or female.

An example is the Marriage Legislation Amendment Bill 2015, sponsored by a cross-party group of MPs including Coalition member Warren Entsch. It sought "to allow couples to marry, and to have their marriages recognised, regardless of sex, sexual orientation, gender identity or intersex status". It went beyond the proposed plebiscite question in defining marriage not in terms of heterosexual or same-sex relationships, but as "the union of two people to the exclusion of all others, voluntarily entered into for life".