Whether or not Australia’s states are monarchies in their own right is a complicated issue. Dr Anne Twomey explores the constitutional issues in her excellent book
The Chameleon Crown: The Queen and Her Australian Governors. It was quite clear-cut before the Australia Acts of 1986. All the states were still under the authority of the Queen of Great Britain, not the Queen of Australia. When a state needed a new Governor, the Premier provided a name to the British Foreign and Commonwealth Office. If the FCO agreed, it would make the formal recommendation to the Queen. But all that changed in 1986.
The state premiers assumed that they would have direct access to the Queen, who would be obliged to accept their advice. There was even a push in Queensland for the Queen to officially become Queen of Queensland. But Canberra and London were not keen on the idea. Canberra did not like the implication of sovereignty, and wanted the Governor-General to appoint state Governors (as the Governor General of Canada appoints the provincial Lieutenant Governors). London was worried the Queen might get dragged into an argument between squabbling states. Eventually a compromise was reached, but how it happened is not quite clear. The relevant sections in Dr Twomey’s book were removed prior to publication, at the request of Buckingham Palace (I suspect the Queen might have intervened). The result is that state premiers advise the Queen directly on the appointment of a Governor. This advice the Queen is obliged to accept. But the Queen is not obliged to accept any other kind of advice from a state premier, unless it has been agreed to beforehand.
This compromise at least excludes the possibility of the Premier of Victoria advising the Queen to sack the Premier of New South Wales. But it is still left an important question unanswered. Which crown is the Queen wearing when she appoints a state Governor? It is clearly not the crown of Great Britain. As a separate state crown probably does not exist, the Queen is probably wearing the Crown of Australia. But this has never been confirmed, and remains open to interpretation.
As to the succession, the states did
not pass legislation to change it. The states’ legislation only
requests that the Commonwealth Government pass legislation to make the appropriate changes. This is in accordance with section 51(xxxviii) of the Constitution of the Commonwealth of Australia:
The Parliament shall, subject to this Constitution, have power to make laws for the peace, order, and good government of the Commonwealth with respect to: .....the exercise within the Commonwealth, at the request or with the concurrence of the Parliaments of all the States directly concerned, of any power which can at the establishment of this Constitution be exercised only by the Parliament of the United Kingdom or by the Federal Council of Australasia
I think this supports the conclusion that the states are not fully separate monarchies, but come under the authority of the Queen of Australia. Prior to the referendum in 1999, the states agreed to change their constitutions if a republic was approved. But what if one or more states decided after the referendum not to change? Could a state government even continue to function? At some point the state would need a new Governor, but who would make the appointment? Not the Queen of Australia, she would no longer exist. How about the Queen of Great Britain? I think the Australia Acts might exclude that option, and the British government would not want the Queen dragged into an Australian constitutional quagmire. The government of a new Australian republic probably would explore all possible ways to force a monarchist state to jump on board, but things could get very complicated.