Commonwealth v ACT (2013) 250 CLR 441 (“The Same-sex Marriage Case”)

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  • Section 51(xxi) of the Constitution provides the Federal Parliament with power to make laws with respect simply to “marriage”.
  • In 2013, the ACT Legislative Assembly passed The Marriage Equality (Same Sex) Act 2013 (ACT) (Equality Act).  This authorised same-sex marriages.
  • It was unclear whether the federal Marriage Act 1961 (Cth) (Marriage Act) intended to “cover the field” in respect of marriage laws in Australia, considering its omission of same-sex marriage.
  • The Commonwealth challenged the Act in the High Court of Australia as inconsistent with the Marriage Act.


  • Was the Equality Act inconsistent with the Marriage Act, despite concerning same-sex marriage?


  • The High Court unanimously held that the Equality Act was inconsistent with the Marriage Act. It was held to be of “no effect.”
  • The definition of “marriage” in the Equality Act was inconsistent with that in the Marriage Act.
  • The Equality Act could not operate concurrently with the Marriage Act, since the Marriage Act was intended to be “a comprehensive and exhaustive statement of the law with respect to the creation and recognition of the legal status of marriage”.
  • The Court did not accept that the Equality Act did not regulate the status of marriage, because the Equality Act’s long-form name conveyed its intention of regulating “marriage equality”.
  • The effect of the Court’s decision was that the Equality Act was of “no effect”, rather than “void”.  The Court used the language of its established interpretation of section 109 of the Constitution.  Section 109  provides that a state law will be “invalid” to the extent that it is “inconsistent” with a federal law.
  • The Court has understood “invalid” in section 109 to mean not that the state law is simply void but that it is “inoperative” for so long as the inconsistency remains; if that federal law were to be changed so as to remove the inconsistency, the state law would revive.


“The utility of adopting or applying a single all-embracing theory of constitutional interpretation has been denied. This case does not require examination of those theories or the resolution of any conflict, real or supposed, between them. The determinative question in this case is whether s 51(xxi) is to be construed as referring only to the particular legal status of “marriage” which could be formed at the time of federation (having the legal content which it had according to English law at that time) or as using the word “marriage” in the sense of a “topic of juristic classification”. For the reasons that follow, the latter construction should be adopted. Debates cast in terms like “originalism” or “original intent” (evidently intended to stand in opposition to “contemporary meaning”) with their echoes of very different debates in other jurisdictions are not to the point and serve only to obscure much more than they illuminate.”

(French CJ, Hayne, Crennan, Kiefel, Bell & Keane JJ at [14])

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