When the Supreme Court hears oral argument April 20 on the cases challenging the legality of the detentions at Guantánamo Bay, Cuba, it will confront the most dramatic conflict between liberty and security it has considered since World War II. The Bush Administration claims that the “war on terrorism” requires that it have unchecked power to detain “enemy combatants”–however the President defines the “war” and its “combatants.” Lawyers who have challenged the Administration’s position, without even getting to consult with the detainees they represent, maintain that if the rule of law means anything, the President cannot lock up human beings indefinitely and deprive them of access to any court.

The fact that the Court agreed to consider the Guantánamo detainees’ claims–at a time when all the lower federal courts had ruled that the doors to the courts were closed–offers some basis for hope. But the Court’s record on matters of national security and noncitizens’ rights is not encouraging. The best hope for a rights-affirming ruling may rest on the Court’s jealousy of its own power rather than on any concern for those who have languished at Guantánamo for more than two years.

The Bush Administration’s position could not be more sweeping. It claims it can warehouse indefinitely at Guantánamo any person the President labels an “enemy combatant,” or as George W. Bush puts it, “a bad guy.” And it asserts that no court can play any role in reviewing its actions, because as foreign nationals the Guantánamo detainees have no rights enforceable in US courts. Under this view, if the military decided tomorrow to summarily execute all 650 or so men currently held captive, there’s nothing any lawyer or court in the world could do about it.

It would be hard to imagine a more extreme assertion of unchecked, arbitrary power. Yet if the Supreme Court is to stand up to the Administration, it will have to depart from its own traditions. First, it has consistently deferred to the executive in times of crisis. It upheld the jailing of antiwar dissidents during World War I and of more than 110,000 Japanese-Americans during World War II. It whitewashed the military trial and execution of German saboteurs during World War II, prematurely announcing that it saw no problem with the trials and only issuing its decision after the executions had been carried out.

Second, the Court has repeatedly stated that foreign nationals outside our borders have no constitutional rights. In two of its most ignominious decisions, the Court in the 1950s held that due process imposed no limit on the government’s detention–on secret evidence–of a German woman and a Hungarian man locked up on Ellis Island for years, because they were foreign nationals who had not entered the United States.

If anything leads this Court, staunchly conservative and pro-government in the best of circumstances, to rule against the Administration, it will be the Court’s sense of its own power. The Administration’s position writes the Court (not to mention Congress) out of the system of checks and balances. It claims that even when it is locking up human beings without a shred of due process, the courts have nothing to say in the matter. But this Court has jealously guarded its power–whether in deciding presidential elections or invalidating acts of Congress. Rarely has the Court been so incensed as when Congress argued, seven years ago, that by enacting the Religious Freedom Restoration Act, it could enforce a more expansive understanding of the free-exercise clause than the Court itself. The Court struck it down in no uncertain terms. More recently the Court even upheld Miranda v. Arizona, a decision a majority of today’s Court would never have written in the first place, when it saw the issue as Congress seeking to question the Court’s power.

In the end, if the Court rules against the Administration, it may be more to protect itself than to protect those in limbo at Guantánamo Bay. But in this instance, I’d take it, because nowhere is it more important for the courts to insist on their authority than in reviewing the power to lock up human beings.