The Abbott Government could choose to make life difficult for David Hicks as he tries to overturn his US conviction on terrorism charges, but he deserves better, writes Greg Barns.

Canberra owes former Guantanamo Bay detainee David Hicks some support. Hicks is appealing against his March 2007 military court conviction (he pleaded guilty while maintaining innocence which is allowable under US law) for providing material support for terrorism, and his lawyers should be able to get a clear run at the appeal without any interference from the Abbott Government.

The Australian Government must answer questions about its knowledge of the horrific crimes committed against Hicks by those who oversaw Guantanamo Bay during the five years he was held there.

Mr Hicks was never a terrorist. He was in the wrong place at the wrong time - a lost soul hanging out with some causes and characters with which the West had taken issue after 9/11. Hicks was captured by the Northern Alliance in Afghanistan in late 2001 and handed over to the Americans. There was never any evidence that Hicks was any more than a fellow traveller with the Taliban.

But what happened to David Hicks at Guantanamo Bay should outrage any decent minded person. Hicks alleges he was sexually assaulted, beaten and tortured during his years in that hellhole that the US leases from Cuba. As Amnesty International has noted:

David Hicks's allegations echo claims that have come not only from detainees, but also from non-detainee sources, including FBI agents who have said they witnessed abuses in Guantanamo

Then there was the cruel farce of the Military Commissions Act passed by Congress at the behest of the Bush Administration and under which Hicks was charged. It allowed for secret trials run by the military, and the invention of criminal charges that would not pass muster in the civilian court system. Hicks' plea bargain was, as Lex Lasry, now a Victorian Supreme Court judge, observed:

... the product of an inherently oppressive and coercive system. The agreement reflects a view on the part of the US authorities that liberty is not a right that may only be denied a person in accordance with strict procedure established by law, but rather liberty is a bargaining chip that the State may use to avoid accountability and buy impunity.

The Military Commissions Act also allowed for retrospective charges to be brought against detainees. But in October last year, the US Court of the Appeals for the District of Columbia Circuit, regarded as second only to the US Supreme Court in terms of its jurisprudence, ruled that the charge of providing material support for terrorism was not in fact a lawful charge. This decision, known as Hamdan, gives David Hicks a chance to seek justice for the first time since his capture in 2001.

Critically, the US Court of Appeals interpreted "the Military Commissions Act of 2006 so that it does not authorize retroactive prosecution for conduct committed before enactment of that Act unless the conduct was already prohibited under existing US law as a war crime triable by military commission ... Material support for terrorism was not a war crime under the law of war" at the time of Hamdan's conduct.

The preponderance of legal opinion in the United States is that the October 2012 decision means that David Hicks, despite pledging not to appeal as part of his plea bargain, ought to have his conviction overturned.

The Australian Government could still make life difficult for David Hicks. Since he came back to Australia in December 2007, courtesy of a political buddies deal between an electorally diving prime minister John Howard and president George W Bush, Hicks was placed on a draconian and completely unnecessary control order under Australia's anti-terror laws. This meant ASIO surveilling his every movement and putting restrictions on what he might or might not do. The Commonwealth DPP pursued Hicks for proceeds of crime application when his book was released in 2011, but fortunately thought the better of it and dropped the application.

No doubt the Abbott Government could call on its chums in the Department of Defence in Washington and in the White House and appeal to them to block Hicks' application. To do so would be churlish, but also endorse implicitly the rogue status of the military 'justice' system set up in the past 9/11 era of irrationality.

What Australia should reflect on is whether or not Canberra is liable for the appalling physical and mental abuse that was inflicted on Hicks at Guantanamo Bay and about which he complained as early as 2002.

Did the Howard government know what was happening to Hicks? Did the Embassy in Washington bother to inquire about the welfare of one of its own citizens? If the answer is that yes, Canberra did know, then more than an apology is owed to Hicks.

David Hicks deserves justice. He was never a terrorist. He was never even linked to Al Qaeda. He was a pawn in the cruelty of the war on terror and he deserves to have no obstacles put in the way of his quest to clear his name.

Greg Barns is a barrister and a spokesman for the Australian Lawyers Alliance. View his full profile here.