"So if prisoners were sent on a boat to the United States, your interpretation is that Congress forbids the president to send them back?" he asked. Keyes responded that the statute applies only to legal immigrants, not illegal aliens.

Currently, a federal judge's nationwide stay prevents the government from removing anyone to Somalia. A judge in Seattle ordered the ban on deportation, which remains in effect as the Supreme Court reviews the case.

Also Tuesday, the court heard arguments in the case of Josue Leocal, a Haitian man fighting deportation after pleading guilty to a felony charge of drunk driving.

At issue is whether a DUI accident that causes injury to others is a "crime of violence" that allows the government to start deportation proceedings against the permanent resident.

Leocal argues a "crime of violence" requires criminal intent or at least recklessness in causing harm — not mere negligence as in his offense; the United States disagrees, saying the wording of the immigration statute doesn't indicate that higher standard. Federal courts are sharply divided on the issue.

On Wednesday the court will consider if immigrants who entered the country illegally and then committed crimes should be constitutionally protected from indefinite detention.

Government lawyers have emphasized the potential terror threat, stating in filings that forcing the release of immigrants "creates an obvious gap in border security that could be exploited by hostile governments or organizations."

The Supreme Court also Tuesday:

• Agreed to consider a pair of cases to flesh out guidelines for when lawsuits belong in federal or state court. One involves the family of a 14-year-old girl who cut her finger on a Star-Kist tuna can; the other involves gas station owners in 35 states seeking to sue Exxon Mobil in a dispute over a discount program.

• Agreed to decide whether Hawaii went too far to keep gasoline affordable for residents when it imposed rent caps on dealer-run stations.

• Sidestepped a dispute over whether Internet providers can be forced to identify subscribers illegally swapping music and movies online.

• Refused to decide whether the Pentagon is constitutionally obligated to give news media access to U.S. troops during combat.

• Declined to step into a dispute over whether a restaurant chain must pay its employees for unused vacation time if they quit or are fired within a year.

• Refused to consider Union Pacific Railroad's appeal of a $30 million damage award to a man partially paralyzed in a railroad crossing collision.