WASHINGTON — The Supreme Court considered Tuesday whether the government can send immigrants back to countries that haven't agreed to accept them, a question that will determine the fate of thousands of Somalis resisting deportation to their war-torn homeland.

The immigration case is one of three being heard this week that seek to delineate the limits of federal authorities, who say they should have wide discretion to send back or indefinitely detain foreigners in a post-Sept. 11 world of heightened terror threats.

The Somali case involves Keyse Jama, a 25-year-old refugee who doesn't dispute grounds for deportation because of a felony assault conviction but says he shouldn't be shipped to a lawless country in no position to take him.

"Congress has expressed an interest in the orderly process of deportation," Jeffrey Keyes, Jama's attorney, told the justices. "The reason to have the requirement of acceptance is so it would be less likely to have them bounced around and come back."

Government lawyers counter that federal law gives them authority to act in a way that supports U.S. security interests. Their inability to do so would be particularly troubling because of Somalia's "observed connection" to terrorist activity, they say.

At issue is whether a president is authorized under immigration laws to deport a legal immigrant to countries such as Somalia who haven't agreed to take them because they lack a functioning government. The statute is silent on that specific point.

More than 8,000 Somalis being held in the United States are either subject to deportation or awaiting hearings. Because it may take years for Somalia to establish a working government, a victory for Jama will likely mean freedom for those immigrants since the Supreme Court has previously declared their indefinite detention unconstitutional.

In oral arguments, justices appeared divided in interpreting the statute in question.

Justice Stephen Breyer proposed a narrow solution that would grant Jama relief from deportation on the grounds that Somalia is not a "country" because it lacks a government.

When government lawyer Malcom L. Stewart resisted, Breyer responded: "You're not suggesting we can deport them to Antarctica or send them to the moon? Antarctica is a country, so we can send them to live with the penguins?"

Justice Antonin Scalia, meanwhile, expressed concern that a president's authority might be unduly constrained if the United States is required to obtain acceptance before deporting immigrants.