[captured Taliban fighter] David Hicks is unlikely...

[captured Taliban fighter] David Hicks is unlikely ever to be tried for treason. Speculation has arisen that he may be charged with treason under the Crimes Act or possibly under the Crimes (Foreign Incursions and Recruitment) Act, which covers hostile activity against a foreign government and mercenary operations.
Treason is betrayal by a citizen of their loyalty to the state or the sovereign - for example, giving secret government documents to an enemy, particularly in wartime.
Even if convicted of treason in Australia, Hicks would certainly not face the death penalty, despite the Crimes Act saying someone convicted of treason was liable to punishment by death.
Professor Gillian Triggs, University of Melbourne's Institute of Comparative and International Law co-director, said this was superseded by the Death Penalty Abolition Act, which replaced the death penalty in all other relevant legislation with life in prison.
"The 1973 Act abolishes the death penalty, in my view," Professor Triggs said.
"The Crimes Act still uses the words `death penalty', and that's the confusion."