The Authorization for Use of Military Force ("AUMF") authorized the president "to use all necessary and appropriate force against those nations, organizations, or persons he determines planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001, or harbored such organizations or persons." The Guantanamo detainees who challenged their detentions in the habeas proceedings before Judge John Bates argued that the president has no authority to detain someone who did not plan, authorize, commit, or aide the 9/11 attacks even if he belonged to an organization that did. In their view, the law of war does not permit the detention of civilians on the basis of their status rather than their conduct.

Judge Bates' decision (pdf) concludes that "the lack of combatant status ... does not, by default, result in civilian status for all, even those who are members of enemy 'organizations' like al Qaeda." Judge Bates reasoned that the Geneva Conventions recognize "a class of individuals who are separate and apart from the 'civilian population' -- i.e., members of enemy armed groups." The law of war, in Judge Bates' view, permits the government to detain individuals because of their associational status; that is, their association with Taliban or al Qaida forces. (Whether an individual is a member of al Qaida or merely sympathetic to its goals is a factual question that turns on whether the individual is part of the organization's command structure; i.e., whether he receives or executes orders.)

The government wanted to go one step further. It advocated the president's authority to detain anyone who "substantially supported" al Qaida (a financier, for instance) even if he was not a part of the organization, as well as anyone who "directly supported hostilities" even if he did not commit a belligerent act. Judge Bates found no support for that proposition in the law of war. Neither did the government.

After repeated attempts by the Court to elicit a more definitive justification for the "substantial support" concept in the law of war, it became clear that the government has none.

In other words, the government threw it out there and hoped it would stick. It didn't. The government borrowed the "substantial support" concept from criminal law, but the detainees at Guantanamo haven't been charged criminally. If the government wants to justify their detention under the law of war, Judge Bates reasoned, it's limited to law of war principles.

All of this is about as clear as the Mississippi River after a three-day thunderstorm. Last month, Judge Reggie Walton accepted the government's argument that "substantial support" of al Qaida justifies detention, as did Judge Gladys Kessler in a more recent opinion (pdf). Notwithstanding her willingness to adopt the government's view of the president's detention authority, Judge Kessler ruled that the government failed to prove that detainee Alla Ali Bin Ali Ahmed fought for, was trained by, or substantially supported al Qaida or the Taliban.

Whether or not the president has the power to detain members of al Qaida indefinitely, Ali Ahmed's case is the latest example of how the power to detain can be (and has been) abused. The simplest and best way to bring clarity to the muddled status of Guantanamo detainees is to rely on the criminal law rather than the law of war. If the detainees committed crimes against the United States, charge them and try them in a criminal court. If they didn't, their detentions should end.