The republicans' preferred argument in the 1999 referendum was that Australia needed an Australian Head of State, and only their (politicians') republic could provide this.
The argument was used nine times in the official Yes No case approved by MP's and Senators and distributed by the Electoral Commission, far more than any other.
This is not a constitutional law term of art. It is a diplomatic term. It is thus governed by international law. Used in relation to the constitution, it is descriptive.
ACM demonstrated that under international law there was no doubt whatsoever that the Governor-General is Head of State: see The Cane Toad Republic, 1999, chapter 3. ( Although Malcolm Turnbull said in his book, Fighting For the Republic, that I am not a constiutional lawyer, I have taught and published in both constitutional and international law.)
..and the constitution?..
There are good reaons to use the term Head of State to describe the constitutional role of the Governor-General: see The Cane Toad Republic, Sir David Smith, Head of State. This usage can be traced back to a unanimous bench of Founding Father Justices of the High Court in 1907. This was first noted in "The Head of State Debate Resolved," Quadrant , July-August, 2008
The republicans have of course confused the issue. It is not surprising that republican policians should be confused; some of them think Canada is a republic.
Incidentally as we noted here, when The Queen addressed the UN in New York, Her Majesty did not say she was Head of State of sixteen realms.
Her Majesty said she spoke "as The Queen of sixteen United Nations member states and as Head of the Commonwealth."
The Prime Minister Julia Gillard is being criticised on the question of the distinction between a head of state and a head of government in relation to her announcement to establish a Regional Processing Centre for asylum seekers or illegal immigrants in East Timor.
While she raised this just before with the Heads of Government of New Zealand and Indonesia, she did not in relation to East Timor.
It was like speaking to the Governor-General of New Zealand and not the PM.
In East Timor she spoke to the Head of State, President Jose Ramos Horta. Under the constitution this is a matter for the Head of Government, Prime Minister Xanana Gusmao, and not the President. It is surprising her advisers did not tell her this.
Tony Jones raised a number of questions about this on the ABC's Lateline on Wednesday, 7 July 2010.
An extract from the interview follows: