They were enacted using legislative powers conferred by enabling acts passed by the parliaments of every Australian state.

The Australia Act (Cth and UK) eliminated the remaining possibilities for the United Kingdom to legislate with effect in Australia, for the UK to be involved in Australian government, and for an appeal from any Australian court to a British court.

[citation needed] The UK Parliament's power to legislate with effect for the Commonwealth itself was mostly ended with the Statute of Westminster 1931, when adopted by Australia in 1942 retroactive to 1939.

Until then, Australia had legally been a self-governing dominion of the British Empire, but with the adoption of the Statute became a (mostly) sovereign state.

[citation needed] In the 1980s, Canada, Australia, and New Zealand all began the process of severing their last constitutional links to the United Kingdom.

Predictably, the High Court proved reluctant to grant certificates for appeal to the Privy Council.

[9] In 1961, delivering on behalf of the whole Court a brief dismissal of an application for a certificate, Chief Justice Sir Owen Dixon said: "experience shows – and that experience was anticipated when s. 74 was enacted – that it is only those who dwell under a Federal Constitution who can become adequately qualified to interpret and apply its provisions".

[10] In 1985, the High Court unanimously observed that the power to grant such a certificate "has long since been spent" and is "obsolete".

[16] However, Queen Elizabeth II was to visit Australia early in 1986 and, in acknowledgement of Australian sensibilities, it was arranged that she would assent to both versions of the Act and then proclaim them so that they would come into force at the same moment in both countries.

[19] The ceremony was presided over by the Australian prime minister, Bob Hawke, to whom the Queen presented the signed copy of the proclamation, along with the assent original of the UK Act.

State laws would no longer be subject to disallowance and reservation by the monarch (s 8) – a power that, anomalously, remains for Commonwealth legislation (Constitution ss 59 and 60).

Thus, for practical purposes, the Australia Act has eliminated the remaining methods of appeal to the Privy Council.

The High Court in Sue v Hill in 1999[23] did not rely upon the long title or the preamble, which conventionally do not have force of law.

One of those who did not find it necessary to express an opinion on this point, Justice Michael Kirby, was in a later case to deliver a dissent in which he argued that section 6 of the Australia Act 1986 (Cth) was invalid.

In Kirby J's view in Marquet (2003),[24] this was inconsistent with Constitution s 106, so that section 6 of the Australia Act (Cth) was not a valid exercise of Commonwealth legislative power.

In Shaw v Minister for Immigration and Multicultural Affairs (2003), the High Court held that the act "gave voice to the completion of Australia's evolutionary independence ... it was a formal declaration that the Commonwealth of Australia and the Australian states were completely constitutionally independent of the United Kingdom".