On March 28, the Supreme Court will hear arguments on whether the "military commissions" created by President Bush in November 2001 to prosecute suspected Qaeda terrorists are a time-honored presidential prerogative or (as I have re- luctantly come to believe) another unwise, unconstitutional Bush power-grab.

The legal issues are complex and difficult, and the outcome is hard to predict. What's already clear beyond dispute, however, is that this supposedly speedy, streamlined system—which took nearly three years to start its first trial—has in practice been a fiasco and an international embarrassment.

Small-fry defendants. Weak evidence. Commission members apparently hand-picked for their likelihood to please their bosses.

Egregious errors by translators. And constantly changing rules, including the last-minute effort to dress up the commissions for their date with the Supreme Court by banning the previously approved use of statements obtained under torture.

The defendant whose case is now before the Court, Salim Ahmed Hamdan, hardly seems to be one of "the most dangerous, best-trained, vicious killers on the face of the earth," as Defense Secretary Donald Rumsfeld has described the Guantanamo detainees. Hamdan admits that he was Osama bin Laden's chauffeur for several years before his capture in late 2001. But he is charged with only a single count of conspiring to murder civilians, based on allegations so nebulous that a real court might well throw the case out. The government has not even claimed that Hamdan helped plot any terrorist attacks or committed any specific criminal act. Its best evidence seems to be that he drove Qaeda members and weapons around Afghanistan.

Was it for this that Bush—who claims the power to detain people such as Hamdan indefinitely without ever prosecuting them—created his own personal prosecutorial system outside the traditional military courts? A system with "crimes" defined and procedures designed by political appointees, with "judges" of doubtful independence, with no appeals outside the chain of command, with possible penalties including death?

The idea of using special military commissions to try people for real war crimes has deep roots in our history and seemed to me a good idea in the abstract. Such tribunals could be designed to meet the war-on-terror need to shield informants from retribution, protect intelligence secrets, and use reliable evidence that would be inadmissible in ordinary courts.

But the commissions proved more difficult to design than I and others had imagined. And Bush, Rumsfeld, and company botched the job. They should have asked Congress to create a few discrete exceptions to the ordinary rules for courts-martial to accommodate the special demands of war-on-terror prosecutions. But as usual, Bush preferred to bypass Congress and do it his way—unilaterally.

The president's model was the 1942 precedent involving eight saboteurs who were caught after being landed by German submarines on Atlantic beaches with orders to blow up military and civilian targets while posing as American civilians. President Roosevelt created a military commission, with guaranteed-to-convict procedures, which secretly tried and condemned the defendants so fast that six of them were executed months before the Supreme Court had finished writing its decision unanimously upholding the process, ex parte Quirin. (Roosevelt had told his attorney general that he would defy any decision not to his liking.)

The Bush White House initially mimicked Roosevelt's patently unfair procedures, reasoning that what was good enough for the Supreme Court during World War II should be good enough 60 years later, in what could be a 60-year war against stateless terrorists. But this plan ran into strong resistance not only among the many civilians who assailed Bush for brushing aside the vast changes in constitutional and international law since Quirin, but also among military lawyers and judges who resented Bush's effort to bypass the many improvements in the fairness of military justice since then.

This opposition forced the Pentagon to tinker repeatedly with the rules, improving them in many ways but delaying their implementation. Meanwhile, the administration steadfastly spurned independent judicial review until Congress insisted upon it by attaching the Detainee Treatment Act to a Pentagon funding bill adopted in January.

What will the Supreme Court make of all this? The justices sent mixed signals in two June 2004 decisions involving detention (not prosecution) of suspected enemy combatants. Eight justices rejected the administration's denial of due process to an American citizen (Yaser Esam Hamdi) captured in Afghanistan. And six justices rejected its position that federal courts had no power to hear claims by foreigners seeking release from Guantanamo or relief from alleged brutality there.

(The Detainee Treatment Act limited the latter decision by channeling all claims directly to the federal appeals court in D.C. and allowing it to hear only appeals from final decisions of tribunals including the military commissions. A threshold question in the Hamdan case is the administration's argument that this confusingly worded provision requires dismissal of pending cases such as Hamdan's.)

The administration itself, on the other hand, claimed victory, because the justices held that the president could detain Hamdi militarily if he were found by an independent tribunal to be an enemy combatant, and used language that appeared to reaffirm the Court's decision in Quirin.

But Hamdan's attorneys stress that Quirin and other Supreme Court precedents and laws upholding military commissions were written—and should be read—narrowly. Indeed, the Court held in 1946 that the Constitution ruled out placing "in the hands of one man the power to make, interpret, and enforce the laws," and it ruled in 1996 that "the Framers harbored a deep distrust of executive military power and military tribunals."

Hamdan's case is unlike Quirin and other Supreme Court precedents upholding military commissions in several respects, his lawyers argue. Three of these distinctions might justify holding the Hamdan prosecution unconstitutional, at least unless and until Congress adopts clear, specific authorizing legislation.

First, Article 36(a) of the Uniform Code of Military Justice specifies that military commissions' procedures "may not be contrary to or inconsistent with" those specified in the code for courts-martial. (Commissions are not required to follow the much more detailed Manual for Courts Martial.) The commissions' rules authorizing use of evidence inadmissible under the code and exclusion of defendants from their own trials to protect secrets may flunk this test.

Second, the enemy in the current war—Al Qaeda—is not a nation-state, controls no territory, is hard to find, and has millions of sympathizers worldwide. So this war may well prove to be the longest in our history by far. And the difficulty of sorting out enemy combatants from innocent civilians in this war calls for especially exacting procedural fairness to avoid erroneous convictions and executions. Past military commissions have been temporary expedients. The justices should not approve presidential creation of a new, semi-permanent second-class justice system for this very different war without explicit congressional approval.

Third, the Court has never upheld use of military commissions to prosecute suspected violations of domestic criminal law or "crimes" defined by the president himself. Such commissions are generally limited to prosecuting violations of the "law of war." Does the charge against Hamdan qualify? The Justice Department says yes. Hamdan's attorneys say no, more persuasively.

This is no mere technicality. The law of war is part of international law. So Bush's military commissions can prosecute only actions defined as criminal by the same Geneva Conventions and other international law doctrines that Bush so disdains when they get in his way.

The law of war criminalizes only actions recognized as crimes by all (or almost all) civilized justice systems. Most nations in Europe and the world have never made it a crime merely to join a conspiracy, let alone to enter an "agreement" as nonspecific as the charge against Hamdan. The reason is that such charges are so nebulous as to invite prosecutorial overreaching. The war-crimes tribunals in Nuremberg, Tokyo, Rwanda, and Yugoslavia, among other authorities, have held that conspiracy does not violate the law of war.

If the justices do rule against Bush in the Hamdan case, they will be doing him—as well as the nation—a favor. Bush has chosen not to put any Qaeda leaders on trial, perhaps to avoid disclosure of the highly coercive interrogation methods used on them. That leaves nobody for the commissions to try except small fry like Hamdan. It also risks trivializing the monstrous crimes of Al Qaeda.

A wise president would by now have seen the military commissions as a mistake and quietly shut them down. A stubborn, arrogant president persists in his mistakes until forced to stop.