The Succession to the Crown Act 2015 (Cth) is an Act of the Parliament of the Commonwealth of Australia, which was enacted at the request of all six Australian states as required by the Australian Constitution. The Australian acts were the final part of the Perth Agreement's legislative program agreed by the prime ministers of the Commonwealth realms to modernise the succession to the crowns of the sixteen Commonwealth realms, while continuing to have in common the same monarch and royal line of succession, as was the case at the time of the Statute of Westminster 1931.