 There is an important difference in the source of power of the Commonwealth to legislate over married and "de facto" relationships.Marriage and "matrimonial causes" are supported by sections 51(xxi) and (xxii) of the Constitution.The legal status of marriage is also internationally recognised whereas the power to legislate for "de facto" relationships and their financial matters relies on referrals by states to the Commonwealth in accordance with Section 51(xxxvii) of the Australian Constitution, where it states the law shall extend only to states by whose parliaments the matter is referred, or which afterward adopt the law.