While the Bush administration contemplates long-term options for detaining the 500 or so foreign nationals still held at the U.S. Naval Base at Guantanamo Bay, it might do well to take a look at the Supreme Court's technical decision last week involving the government's power to detain in the United States those non-citizens whose home countries won't accept their return. As a matter of statutory interpretation involving the complexities of federal immigration law, the decision is unremarkable. But as a harbinger of what the White House is likely to encounter as it continues to assert the power to indefinitely detain foreign nationals caught up in the “war on terrorism,” the Court's jurisprudence is becoming impressively clear.

The Court's latest opinion on indefinite detention comes in the case of Daniel Benitez -- a refugee who arrived in the United States from Cuba as part of the Mariel boatlift almost 25 years ago and who has been legally without a country ever since. Paroled into the United States with more than 100,000 of his countrymen but never officially “admitted,” part of a legal fiction designed to deal with the massive influx of refugees, Benitez eventually applied to become a lawful permanent resident of the United States. By that time, Benitez had been convicted of theft, making him ineligible for permanent resident status and indeed subject to removal from the country. But when U.S. authorities sought to invoke these grounds to expel Benitez from the United States in 2001, Cuba was unwilling to take him back. Unwelcome in Cuba and inadmissible in the United States (despite having lived here for more than 20 years), Benitez was stuck -- detained by U.S. immigration authorities indefinitely, well beyond the 90 days permitted by statute for those subject to removal from the United States.

The question of what to do with stateless immigrants is not new to this Supreme Court. In a 2001 decision, handed down two months before September 11, the Court had held that removable aliens -- aliens who had been legally admitted to the country but were later found subject to deportation -- could not be imprisoned pending deportation indefinitely if their home country refused their return. Instead, a closely divided Court concluded that the indefinite detention of stateless non-citizens would present a “serious constitutional question” and, so, construed the federal statute authorizing their detention to avoid the issue -- allowing detention only so long as “reasonably necessary” to effect removal. After that (presumptively a period of six months), if the detainee could show that there was no significant likelihood of removal in the foreseeable future, the detainee was to be considered for supervised release.

On its face, the difference between that 2001 case, involving European refugee Kestutis Zadvydas, and Benitez's case was a bureaucratic technicality: Zadvydas had been formally “admitted” to the United States, whereas Benitez had been “paroled” into the country. There was no reason evident in this distinction why Zadvydas should have a greater constitutional interest in avoiding indefinite detention than Benitez. But, atmospherically at least, it was impossible to divorce the Court's consideration of indefinite detention this time from the other broad federal detention powers the Bush administration has asserted in the post-September 11 world. Indeed, the government here had argued vigorously that for the Court to impose some sort of time limit on the executive's power to detain foreign nationals in this context would “have significant foreign policy and security implications for the United States,” an area in which the Court should fear to tread. As the government's brief put it: “Any diminution in the political Branches' comprehensive control over the borders, the admission of aliens, and the management of international migration crises would render the Nation more vulnerable to manipulation and infiltration by hostile powers.”

In the end, however, the decision was not even close. The Court held, 7-2, that the same federal law it interpreted in 2001 that authorizes the detention of foreign nationals who have been found “removable” applies in the same way (and with the same limits) to the detention of foreign nationals who had been found “inadmissible.” A non-citizen without a country who had been ordered removed could be held only as long as “reasonably necessary” to deport him. After that, if there was no significant chance that the United States would find a place to send him, he is eligible for release.

Critically, both Justice Antonin Scalia's opinion for the majority and Justice Sandra Day O'Connor in concurrence addressed the government's national security concerns directly. Congress had already passed, as part of the 2001 PATRIOT Act, a provision authorizing prolonged detention, six months at a time and renewable indefinitely, of any alien who could not be removed and who presents a threat to national security. If this were a case about a suspected non-citizen terrorist, the justices implied, Congress appeared to have given the government separately all the power it needed. If the executive still thought that detention power still inadequate, it was more than welcome to go back to Congress for further statutory powers (and face the PATRIOT critics' concerns). But in the meantime, the power to detain non-citizens indefinitely would not be read into statutes lightly, whatever the Executive might say he needs.

Read as of a piece with the Court's landmark rulings last term in the cases of “enemy combatants” held in the United States and at Guantanamo Bay, it seems clear that a significant majority of the Court is unwilling to defer to the executive's assertion, without more, of U.S. national security interests as a justification for indefinite detention. For Benitez, and for the estimated 1,000 to 2,000 others currently in similar circumstances, this means some limited chance to make a life in the United States somewhere outside of a detention cell. For those tasked with crafting a long-term plan for detention in the interest of national security, it means having a long, detailed, and difficult conversation with lawmakers on Capitol Hill. Executive say-so alone is not enough.

Deborah Pearlstein is director of the U.S. Law & Security Program at Human Rights First (formerly the Lawyers Committee for Human Rights) and a visiting lecturer on human rights and national security at Stanford Law School. She clerked for Justice John Paul Stevens during the Supreme Court's 1999-2000 Term.