The news that the US Court of Military Commission Review has dismissed the conviction against David Hicks, the first prisoner convicted in Guantanamo's much-criticised military commission trial system, calls the future of the entire system into doubt. Hicks, an Australian seized in Afghanistan, had undertaken military training, although there was never any proof that he had engaged in combat with anyone, let alone US forces.

In March 2007, he accepted a plea deal in his trial by military commission, admitting to providing material support for terrorism, convinced that it was his only way out of Guantanamo, and waiving his right to appeal. In return, he received a seven-year sentence, although all but nine months were suspended. He was repatriated the following month, and was released in December 2007. Since then, he has fought to clear his name, and has finally been vindicated in a ruling that, importantly, also overturned the waiver against lodging an appeal.

This is the fourth humiliation for the military commissions, which have only reached results in the cases of eight men in total since they were first revived in November 2001.

Salim Hamdan

In October 2012, the conviction against Salim Hamdan, a driver for Osama bin Laden, who had been given a five-month sentence after a trial in July 2008, was thrown out by the court of appeals in Washington DC (the DC Circuit Court) on the basis that it was not a recognised war crime at the time the legislation establishing the commissions was passed.

Reading between the lines, what this really meant is that it was invented by Congress in 2006 after the first version of the commissions had been thrown out by the Supreme Court for violating the Uniform Code of Military Justice and the Geneva Conventions.

This was made clear in 2009, when the Obama administration, having put a hold on the commissions when Obama took office, revived them for a third time. In testimony to the Senate, David Kris, a Justice Department lawyer, and Jeh Johnson, the Pentagon's senior lawyer, pointed out that the charge of providing material support might well be the subject of successful appeals. Both men, however, were ignored.

In January 2013, the DC Circuit Court threw out the conviction for material support against a second prisoner, Ali Hamza al-Bahlul, a Yemeni who had made a promotional video for al-Qaeda. Bahlul had failed to mount a defence in his trial in October 2008, but had, nevertheless, received a life sentence. Further proceedings have failed to establish whether or not Bahlul's conviction for another charge, conspiracy, should stand, but the dominoes have continued to topple.

With the commissions crumbling around them, it is unclear if the system can survive. Seven men ... are currently the subject of seemingly interminable pre-trial hearings ...

On January 9, 2015, a third prisoner, Noor Uthman Muhammed, from Sudan, had his conviction thrown out by the convening authority for the commissions. Muhammed, who worked at a military training camp in Afghanistan, accepted a plea deal in February 2011, pleading guilty to providing material support and conspiracy, in exchange for a 14-year sentence, of which all but 45 months was suspended. He was repatriated in December 2013.

Questions must be asked

With Hicks' conviction overturned, there are now only four convictions that remain, and some of these look tenuous.

Ibrahim al-Qosi, a Sudanese cook, accepted a plea deal in July 2010 for providing material support, and was repatriated two years later. His conviction is clearly no longer valid, but questions must be asked, too, about the conviction of Omar Khadr, a former child prisoner who, as a juvenile, should never have been put on trial at all.

In October 2010, Khadr agreed to a plea deal in which he pleaded guilty to murder and attempted murder in violation of the laws of war, and to spying, as well as conspiracy and material support, and he is currently serving an eight-year sentence in Canada. One of his lawyers, Nate Whitling, called the Hicks ruling "important," and said it "confirms that the form of waiver signed by Omar as part of his plea deal is invalid, and that he may appeal all five of his convictions".

Two other men, Majid Khan and Ahmed al-Darbi, have agreed to plea deals, but have not yet been sentenced. However, with the commissions crumbling around them, it is unclear if the system can survive.

Seven men, including Khalid Sheikh Mohammed, are currently the subject of seemingly interminable pre-trial hearings, as their lawyers seek to expose evidence of their torture in "black sites", while prosecutors try to make sure that no mention of their torture is ever made public. Instead, it would make sense to abandon the commissions, and to move these men to the US mainland for federal court trials.

This should have happened when they were first seized, in some cases over a decade ago. It would mean that justice might finally be delivered, and be seen to be delivered, and it would also help Obama to fulfil his long-delayed promise to close Guantanamo.

Andy Worthington is a freelance investigative journalist.

The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.