Sir Ninian Stephen, Governor-General of Australia, assented to the Australian Act on 4 December 1985 and it came into effect on 3 March 1986 by a proclamation signed by Queen Elizabeth II at Government House, Canberra. Enabling legislation to bring the UK and Australian Acts into force was passed by the parliaments of the United Kingdom and each of the Australian states.
One of the most significant effects of the Act was the termination of appeals from Australian courts to the British Judicial Committee of the Privy Council. Section 74 of the Constitution provided that the Parliament of Australia could make laws to prevent appeals to the council, and it did so, beginning in 1968, with the Privy Council (Limitation of Appeals) Act 1968, which closed off all appeals to the Privy Council in matters involving federal legislation. In 1975, the Privy Council (Appeals from the High Court) Act 1975 was passed, which had the effect of closing almost all routes of appeal from the High Court. However, appeals to the Privy Council from the Supreme Courts of the states remained open.
Section 11 of the Australia Act had the effect of closing off such appeals from the state Supreme Courts. Only one theoretical avenue of appeal remains since the passing of the Australia Act, the one set out in section 74 of the Constitution, which bars all appeals to the Privy Council on inter se questions (disputes about the limitations of constitutional powers between the Commonwealth and the states, or between the states themselves) unless the High Court grants a certificate allowing the appeal. While the High Court may still theoretically grant such a certificate, the High Court stated in Kirmani v Captain Cook Cruises (No 2) that the jurisdiction to grant such a certificate "has long since been spent" and is obsolete. Thus for practical purposes, the Australia Act eliminated the remaining avenues of appeal to the Privy Council.
Another function of the Australia Act was to establish some form of independence to the states of Australia. Imperial Acts such as the Statute of Westminster 1931 granted the Commonwealth of Australia various degrees of nationhood, but failed to apply to the State Governments. Because of this, prior to the passage of the Australia Act, these states essentially remained colonies under the British Crown. For example, the British government retained the right to advise the monarch on her choice of state governors.
The revamping of constitutional arrangements at both federal and state level required each state parliament to pass its own enabling legislation. The long title of these state Acts (such as the Australia Acts (Request) Act 1985 of New South Wales) were "An Act to bring constitutional arrangements affecting the Commonwealth and the States into conformity with the status of the Commonwealth of Australia as a sovereign, independent and federal nation." Collectively the federal, state and British Acts were known as the "Australia Acts".