Attorney-General Christian Porter says having a governor-general with the power to sack a prime minister keeps governments on their toes.
The release of previously secret letters between Sir John Kerr and the Queen has sparked debate around the role of the governor-general and whether Australia should become a republic.
It has also reignited discussion around the governor-general's "reserve powers", which he or she can exercise without ministerial advice or even contrary to ministerial advice.
Reserve powers generally include such things as the power to appoint a prime minister if an election results in a hung parliament or dismiss a prime minister in the event of a no confidence motion in the lower house.
But Sir John's decision in November 1975 to dismiss Gough Whitlam, who had the confidence of the House of Representatives but was unable to secure money "supply" in the Senate, remains the most controversial use of the reserve powers.
Mr Porter said the existing system had served Australia well.
"I think that many people who argue that 1975 was an event that should be an event that pushes us towards a republic don't like the fact that there's any degree of uncertainty in the system," he told 6PR radio on Wednesday.
"But I wouldn't conceive of this as being unclear or uncertain. We know what the governor-general can do, we've seen it done and it's that power that keeps executive governments on their toes."
Australian Republic Movement national director Sandy Biar said the letters showed Buckingham Palace provided advice on how Sir John might exercise his reserve powers and helped wargame scenarios with the then governor-general.
"Without the explicit assurances of the palace, Sir John Kerr may not have acted," Mr Biar said.
A statement issued by Buckingham Palace said the Queen had "consistently demonstrated this support for Australia, the primacy of the Australian Constitution and the independence of the Australian people, which the release of these letters reflects".
The letters confirmed that neither the Queen nor the royal household "had any part to play in Kerr's decision to dismiss Whitlam", the statement said.