Guantanamo Bay Naval Base, Cuba ? Critics of the use of Military Commissions for war-on-terror captives here say an Australian prisoner’s decision to plead guilty does not absolve the U.S. government of the need to fix a court whose rules differ from both standard U.S. military or civilian justice.

Instead, even as military lawyers were meeting privately here to work out the terms of David Hicks’ agreement to plead guilty to supporting al-Qaida, they described his guilty plea as a “Get Out of Guantanamo Card” from a fatally flawed system.

“Hicks’ guilty plea should not be seen as legitimizing in any way the utterly illegal system of off-shore penal colonies, abuse and trials that violate fundamental due process rights,” said Vince Warren, executive director of the New York Center for Constitutional Rights, which has filed suits on behalf of hundreds of captives here.

Hicks was the first captive to be charged and would have been the first tried at commissions, which were approved by Congress in September, even as the Pentagon is still promulgating rules. The chief prosecutor has predicted he might put on trial as many as 80 of the 385 men held as “enemy combatants.”

Yet Hicks, 31, has been a bit of an anomaly here as one of the few remaining Westerners in the camp. And, unlike any other captive, his government had a diplomatic deal with the Bush administration to let Hicks serve out any sentence based on a military commission conviction in his native land.

“It is likely he pled guilty to the charge of providing material support in order to serve his time in Australia and leave the black hole of Guantanamo,” Warren said.

Neither of the next two captives who could next be charged have similar deals.

One, Canadian Omar Khadr, had earlier challenged efforts to try him as a war criminal on grounds he was a “child soldier,” aged 15 at the time of his capture in a 2002 firefight in Afghanistan that killed U.S. Army Sgt. Christopher Speer, a Special Forces medic.

And the other, Osama bin Laden’s former Kandahar driver, Salim Hamdan of Yemen, has argued, like Hicks, that his activities did not constitute war crimes. Hamdan challenged the Bush administration’s first military commission system all way to the Supreme Court, which ruled it unconstitutional.

Bush administration advocates say trial before U.S. military officers using classified evidence, in some instances hearsay and coerced testimony, are national security necessities in an ongoing war on terror.

Opponents of the system say any trials should be conducted by the already established strict rules that govern U.S. military courts-martial or civilian U.S. district courts.