Legal implications of an Australian Plebiscite on Same Sex Marriage

A FEATURE by Professor Gerard Carney, Curtin Law School

Outside Dublin Castle on 15 May 3015. Credit Salt Lake City Tribune.

Outside Dublin Castle on 15 May 2015. Credit Salt Lake City Tribune.School, September 2016 

Whatever the political motivation for the holding of a national plebiscite on the issue of same sex marriage, the legal and constitutional implications are fairly clear. The outcome is merely an expression of electoral opinion on the issue. It has no legal or constitutional effect. The Government and Parliament are legally entitled to ignore the outcome.

This differs from a constitutional referendum held pursuant to s 128 of the Australian Constitution, which if successful, results in a binding amendment to the Constitution. In such a case, the specific amendment has already passed the Australian Parliament, so it takes effect upon referendum approval. That is, passed by a bare majority of the electors nationally and in at least 4 of the 6 States.

Plebiscites are quite rare at the federal level. Only three since federation: the first two in 1916 and 1917 on military conscription both failed; and the third was the selection in 1977 of Advance Australia Fair as the national anthem from four options, achieving the highest approval rating of 43.29%. They have been used more often at the State and Territory level.

Constitutional referenda at the federal level are more numerous, although their success rate is low with only 8 amendments approved out of 44 proposed changes since 1901.

Marriage, as a legal relationship throughout Australia, is presently defined and regulated by the Commonwealth’s Marriage Act 1961 (Cth) as a union between a man and a woman. This Act falls within the Commonwealth Parliament’s power in s 51(xxi) to make laws with respect to “marriage”. Significantly, the High Court of Australia in 2013 held that this power authorised the Commonwealth Parliament to enact legislation to recognize same sex marriage. It also found the ACT law authorizing same sex marriages in its territory to be invalid, being inconsistent with the current Marriage Act 1961 (Cth). This decision also deprived the States from permitting same sex marriages.

Consequently, only the Commonwealth Parliament has the constitutional authority to provide for same sex marriages in Australia. The Parliament could do this simply by amending the Marriage Act. No constitutional referendum is required. Nor any plebiscite. A constitutional referendum would only be required if there was support for entrenching same sex marriage as a constitutional right to prevent any future change by a later Parliament.

Ireland held a successful constitutional referendum on this issue in May 2015 because its Constitution was assumed to implicitly deny recognition to same sex marriage. Australia’s Constitution, on the other hand, leaves the issue to the Parliament to decide.

The appropriateness of holding a plebiscite is therefore an entirely political issue. Given their rarity at the federal level, one naturally asks why a plebiscite on this issue when other controversial social changes, such as divorce on demand, were simply voted on by both Houses of Parliament. One might have hoped that the risk of a small minority in Australia arousing irrational feelings on same sex marriage, such as occurred in Ireland during its referendum, would deter the holding of a legally unnecessary plebiscite here. Far preferable under those circumstances to allow the members of the Australian Parliament, as their fellow brethren did in Canada (2005), New Zealand (2013) and the UK (2013), to undertake the legislative role they were elected to perform.

September 2016.


Gerard Carney was formerly Dean of Law at the University of Queensland, and is currently teaching Law in Perth at Curtin University. He specialises in Constitutional Law.

3 thoughts on “Legal implications of an Australian Plebiscite on Same Sex Marriage

  1. Re para 7: Is the Aust. Constitution silent or specific on the matter? If silent, whose assumption carries the day? And, the US provided picture has a dodgy looking caption!

    • Thanks, Reg, for heads up on error in caption. Fixed. I’ve also alerted the writer to your question. Ed.

    • Hello Reg. The Constitution is silent on the issue. But as it gives the Cth Parliament a power over marriage, it leaves the issue with the Parliament to decide. So Parliament is free to allow or disallow same sex marriage. At present, it disallows it. Does that resolve your query? Regards, Gerard

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