Section 51(xxxvii) of the Constitution of Australia (also called the referral power) is a provision in the Australian Constitution which empowers the Australian Parliament to legislate on matters referred to it by any state. As Australia is a federation, both states and the Commonwealth have legislative power, and the Australian Constitution limits Commonwealth power (see Section 51 and Section 52). Section 51(xxxvii) allows for a degree of flexibility in the allocation of legislative powers.
In practice, the referral power has been quite important in allowing the Commonwealth to enact legislation.