The Australia Act 1986 is often raised by OPCA adherents in Australia as having replaced the Commonwealth Constitution 1901 without referendum. This is factually incorrect as it was solely to do with the States relationship with the UK not the Commonwealth. The theory is based on a misconception of the changes to constitutional relations between Australia and the UK that had already occurred decades earlier. As stated in the preamble, its purpose was:
“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.”
The Australia Acts were put in place to properly separate UK law from the law of the Australian States. By their introduction, they solved a legal problem that occurred with the Balfour Declaration 1926, and the Statute of Westminster Act 1931, where the UK declared they will no longer legislate for “the dominions” (Canada, India, New Zealand, Australia etc).
While the Statute of Westminster Adoption Act 1942 cut legislative ties between the Federal Parliament and UK Parliament, UK law from before the Statute of Westminster Act that was intended for the States (or former Colonies), and UK law in general, was still able to be used for State affairs. UK Acts that were around before 1931 were stuck in a kind of legal ‘time warp’, where even if UK Parliament repealed a UK Act it would still apply to State law. For instance, many Australian states were still using old UK shipping laws in 1931 and never bothered to write their own. When the UK amended their shipping Acts the amendments had no effect on Australian law (since the UK declared they would no longer legislate for the dominions, they could also no-longer repeal or amend the laws of the dominions), some Australian states were still stuck in the old laws, which caused havoc with trade disputes, resulting in many a judge putting their head through a wall in frustration.
Another problem was that State courts could bypass the High Court in appeals and go straight to the Privy Council in the UK, causing further headaches in Australia’s court system, since the High Court still had to answer to the UK privy council. In legal terms, the Australian law system was in a tangled mess that no parliament in the world had the power to solve. In almost Monty Python hilarity, the UK couldn’t even undo their own error, as they had legally bound themselves to not legislate for any of the dominions.
In the end, the solution was found in Section 51 (xxxviii) which gives the Commonwealth Parliament power to legislate at the request of the State parliaments. The State parliaments passed various Request Acts giving the Commonwealth Parliament the ability to pass the Australia Act (Cth).
This was backed by the Australia Act (UK) just in case there was any absence of power on any level, which gained its authority from section 4 of the Statute of Westminster 1931, which provides: “No Act of Parliament of the United Kingdom passed after the commencement of this Act shall extend, or be deemed to extend, to a Dominion as part of the law of that Dominion, unless it is expressly declared in that Act that that Dominion has requested, and consented to, the enactment thereof.”
This officially made the Commonwealth and State constitutions Australian property, and gave Australia complete independence from the UK. It also cut the Privy Council out of the States court system, continuing from previous legislation that enabled this on a federal level. All appeals to the Privy Council from Australian courts exercising federal jurisdiction were abolished in 1968 (Privy Council (Limitation of Appeals/Act 1968 (Cth) and all appeals from any decision of the High Court (other than those where a certificate might be granted under section 74 of the Constitution) were terminated by the Privy Council (Appeals from the High Court) Act 1975 (Cth). See article regarding Appeals to the UK Privy Council.
The Commonwealth Parliament did not require the use of a section 128 referendum, because the Australia Act 1986 did not alter any part of the Commonwealth Constitution, nor was there any intention of altering the Constitution, as stated in the Australia Act itself, in Section 5:
“Commonwealth Constitution, Constitution Act and Statute of Westminster not affected: Sections 2 and 3 (2) above – (a) are subject to the Commonwealth of Australia Constitution Act and to the Constitution of the Commonwealth; and (b) do not operate so as to give any force or effect to a provision of an Act of the Parliament of a State that would repeal, amend or be repugnant to this Act, the Commonwealth of Australia Constitution Act, the Constitution of the Commonwealth or the Statute of Westminster 1931 as amended and in force from time to time.”
While it is true that Justice Michael Kirby delivered a dissent in Attorney-General (WA) v Marquet (2003) HCA 67 this was not due to a lack of a section 128 referendum. He argued that the Australia Act was invalid because section 106 of the Constitution guarantees that a State constitution may be altered only in accordance with its own provisions, hence not by the Commonwealth Parliament. However, Sections 50 and 51 of the Constitution Act 1889 (WA) were altered by section 14 of the Act, and sections 11 and 14 of the Constitution Act 1867 (QLD) were altered by section 13 of the Act. In Kirby’s view was that this was inconsistent with Constitution section 106, so that the Australia Act was not a valid exercise of Commonwealth legislative power. A majority, however, thought that it was sufficient that the Act had been passed in reliance on Constitution section 51(xxxviii), which gives the Commonwealth parliament power to legislate at the request of the State parliaments.
Soon afterwards, however, in Shaw v Minister for Immigration and Multicultural Affairs (2003) HCA 72, the whole Court (including Kirby) took a more comprehensive view: that the Australia Act in its two versions, together with the State request and consent legislation, amounted to establishing Australian independence at the date when the Australia Act came into operation, 3 March 1986. Kirby J. (from 108):
“In Attorney-General (WA) v Marquet (2003) 202 ALR 233 I expressed my reservations about the validity of the relevant parts of the Australia Acts invoked in that case. I contested the proposition that, in 1986, the United Kingdom Parliament had any legislative power to enact a law with respect to Australia’s constitutional arrangements. Such power in my view belongs, and in 1986 belonged, only to the Australian people and their legislatures. So far as the federal Act is concerned, the stream could not rise higher than the source. It could not enlarge federal constitutional power or make it greater than it was. Nor, in my opinion, did s 51(xxxviii) of the Constitution provide a source for the validity of the federal Act. That Act was subject to the provisions of Chs III and V of the Constitution, including provisions with respect to the States and the requirements of s 128 concerning alteration of the Constitution. However, in Marquet, my view was not adopted by the majority of this Court. Pending a greater enlightenment, I must accept this Court’s holding that the Australia Acts are valid laws.”
These two decisions from the High Court are referred to whenever the contention arises in any other court in Australia disputing the validity of the Australia Acts, as has occurred many times in the Supreme Courts of the States. You can locate these cases on this website under the Tag “Australia Acts 1986“. Some of the most recent cases demonstrate the binding nature of these decisions on the Supreme Courts, such as in Southdale Stud Pty Ltd v RJR Trading Pty Ltd  SASC 106 (at 26):
“The appellant has not raised any argument of merit that is capable of challenging the validity of the Australia Act at all. Further, the existence of this Court is not dependent on the validity of the Australia Act. In any event, as the respondent submits, it is not for this Court to depart from what is manifestly ‘seriously considered dicta’ of the High Court as to the validity of the Australia Act, even if, against all probability, I had concluded that the Notice of Appeal contained a proposition of merit. (See Farah Constructions v Say-Dee Pty Ltd (2007) 230 CLR 89 (at 134, Gleeson CJ, Gummow, Callinan, Heydon and Crennan JJ.)”
Likewise in Commonwealth Bank of Australia v Haughton  SASC 135 (at 44):
“There is nothing in the argument to which Mr Haughton took me that affects the outcome in Marquet, nor the ruling later made in Shaw v Minister for Immigration and Multicultural Affairs. Ultimately, this point goes nowhere. .. Even if this is merely regarded as seriously considered dicta of the High Court, it remains binding on me, Farah Constructions Pty Ltd v Say-Dee Pty Ltd (2010) 230 CLR 89,  (Gleeson CJ, Gummow, Callinan, Heydon and Crennan JJ).”
There was also an argument that the Australia Act 1986 altered certain entrenched provisions of the constitutions of Queensland and Western Australia without the referendum required by these State constitutions. Section 11 of the Constitution Act 1867 (QLD) is entrenched by section 53 of the Act, which requires a referendum if the Queensland Parliament wants to expressly or impliedly provide for the alteration of the office of the Governor of Queensland or “in any way affects” the specified sections.
The argument proceeds that the Australia Acts (Request) Act 1985 (QLD) requested the enactment of Commonwealth legislation which would alter the office of the Governor of Queensland and that the Queensland Act therefore required approval in a referendum in order to be valid. The argument concluded that the Australia Act 1986 is invalid because it was not enacted pursuant to a valid request from all the affected States.
This argument was rejected by the Queensland Court of Appeal in Sharples v Arnison  2 Qd R 444, and by the Federal Court in Kelly v Campbell  FCA 1125. The fundamental flaw is that the Australia Acts (Request) Act 1985 (QLD) did not of itself have the effect of expressly or impliedly altering the office of Governor. It merely requested the Commonwealth and Westminster Parliaments to do so. A request for a change does not itself affect the existing law. The request may, indeed, be rejected. If so, there could be no effect upon the law.
The assumed invalidity of the Australia Acts 1986 in reference to these entrenched provisions being altered without referendum was also rejected by the High Court in Attorney-General (WA) v Marquet (2003) HCA 67.
In Western Australia, the same contention was rejected regarding sections 50 and 51 of the Constitution Act 1889 (WA) by their Supreme Court in Sprlyan v Wyborn  WASC 227, referring (at 296) in agreement with the reasoning of the decision in Sharples v Arnison noting that before and after Sharples, single judges of that court had reached conclusions to more or less similar effect.
The Australia Act 1986 (Cth) was passed in reliance on section 51(xxxviii) of the Constitution, which gives the Commonwealth Parliament power to legislate at the request and consent of the State parliaments.
The Governor-General of Australia, Sir Ninian Stephen, had reserved the Act for Her Majesty’s pleasure, and upon receiving her approval, assented to the Australia Act (Cth) according to section 58 of the Constitution, on 4 December 1985, which would come into force on a date to be fixed by Proclamation.
Queen Elizabeth II personally assented to the Australia Act 1986 (UK) on 17 February 1986, which would come into force on a date to be fixed by Proclamation.
On 24 February 1986 she proclaimed that the Australia Act 1986 (UK) would come into force at 0500 Greenwich Mean Time on 3 March.
The Queen then came to Australia, and at a ceremony held in Government House, Canberra, on 2 March 1986, Queen Elizabeth II signed a Proclamation that the Australia Act (Cth) would come into force at 0500 GMT the following day, 3 March 1986. (See Commonwealth of Australia Gazette No S 85 of 2 March 1986, page 87)
Thus, according to both UK law and Australian law, the two versions of the Australia Act would commence simultaneously—the UK version at 0500 GMT in the UK and, according to the time difference, the Australian version at 1600 AEST in Canberra.
Queen then presented the signed copy of the Proclamation, along with the Assent original of the Australia Act 1986 (UK) to the then Australian Prime Minister Bob Hawke. As seen here Elizabeth II personally signed the Proclamation to bring the Australia Act into law herself.
There is a misconception that the Royal Sign Manual being placed on the top of the document somehow invalidates the document and her “permission”, or oversight. See the article “The Queen signed it at the top!” where Wayne Glew‘s remarks that the Royal Sign Manual on the Australia Act 1986 is a forgery because it reads “Elyabeth” instead of “Elizabeth” is also addressed.