Be careful what you wish for. The Supreme Court’s November 10 announcement that it will review two cases challenging the detention, at Guantánamo Bay, Cuba, of foreign nationals as “enemy combatants” surprised many. The lower courts had unanimously ruled for the government. The Supreme Court rarely takes cases where the federal government has won below, and even more rarely where there has been no disagreement among the lower courts. So civil libertarians were heartened to hear that the Court had agreed to hear the cases. The detainees would probably be even more encouraged–that is, if they were allowed to know that the cases exist.

But getting the Court to grant review and winning the cases are two very different matters. The Supreme Court’s past record does not inspire confidence. In times of crisis, the Court has almost always deferred to government claims of national security, no matter how unfounded–most infamously, in Korematsu v. United States, which upheld the internment of Japanese-Americans during World War II.

And in 1950 the Court ruled that federal courts lacked jurisdiction to review the convictions of German “enemy aliens” tried and sentenced abroad for war crimes–a decision the lower courts found determinative in the Guantánamo cases.

Why, then, did the Court even grant review? It may be that the international furor over Guantánamo was simply too widespread for the Court to duck. We are, after all, holding citizens of forty-two different countries there, incommunicado, in solitary confinement, with no hearings or charges and with no sign of release for the foreseeable future. Or the Court may have been disturbed by the Bush Administration’s breathtaking assertion of unchecked authority–it contends that it can pick up foreign citizens anywhere in the world, spirit them off to Guantánamo and lock them up forever, with no court questioning its actions, and therefore without any legal limits.

Now that the Court has accepted review, the Guantánamo cases are significant for three reasons. First, they will mark the Court’s first confrontation with the question of whether and to what extent wartime authority extends to the “war on terror.” The extraordinary powers granted to the executive during wartime are predicated on the assumption that war is an exception to the norm. But the “war on terror,” defined by the Administration as a war on all terrorist groups of potentially global reach, is a permanent condition. It is one thing to rule that in a declared war, the military can try and convict soldiers of war crimes for fighting for the enemy. But to extend that power to hold people indefinitely without trial in an undeclared and permanent war against unidentified foes would reverse the presumption that wartime powers are the exception to the norm.

Second, the cases test the boundaries of fundamental rights. Under constitutional and international law, the right not to be locked up arbitrarily is not restricted to those holding a US passport. Yet the government argues that because the detainees are foreigners held outside our borders, they can be deprived of their liberty without any process. The Court has often suggested that while foreign nationals within our borders are protected by the Constitution, those outside our borders are not. But surely the more defensible view is that the Constitution’s limits apply wherever the government imposes its obligations on people against their will. The right of a human being not to be put behind bars without a hearing should not turn on the vagaries of whether he is held at Guantánamo Bay, Cuba, or Fort Myers, Florida. While battlefield realities may radically restrict the process that is due, it cannot be the rule that due process goes out the window whenever the government calls its initiative a “war.”

Third, the Guantánamo cases involve much more than the rights of foreign nationals. The government’s ultimate argument turns not on the status of the detainees but on the war power itself, which it contends bars courts from second-guessing military detentions. Under the war power, enemies are enemies, whether foreign nationals or US citizens. Thus, the government has invoked the same “enemy combatant” authority to arrest two US citizens, Yasser Hamdi and José Padilla. Given its decision to hear the Guantánamo cases, it seems likely that the Court will also address the detention of US citizens. Its decision in the Guantánamo cases may set the ground rules for all.

No judicial function is more essential to the rule of law than the obligation to decide whether a person thrown behind bars is legally detained. The danger posed by the Guantánamo cases is that the Court will shirk this most critical responsibility and relegate the detainees to a permanent lawless state. If it does so, the Guantánamo cases may go down in history as Korematsu II.