Rights Ruling a Compromise

Since then, it has been used in cases against such defendants as Radovan Karadzic, the Bosnian Serb leader allegedly responsible for mass killings of Muslim civilians, and Unocal Corp., the petroleum multinational that is fighting a lawsuit over its alleged collaboration with the use of forced labor by Burma's government on a natural gas pipeline.

The Supreme Court had stayed out of the battle over the law. As recently as 2001, the court turned down an appeal by Royal Dutch Petroleum Co. in a suit by the survivors of Ken Saro-Wiwa, the human rights activist executed by Nigeria's government in 1995.

But since Sept. 11, 2001, several federal appeals judges who opposed the post-1980 interpretation of the ATS have written dissenting or concurring opinions urging the justices to clarify the law.

Justice Antonin Scalia, joined by Chief Justice William H. Rehnquist and Justice Clarence Thomas, objected to the part of Souter's opinion that permitted some suits under the ATS.

Scalia protested that the majority -- Justices John Paul Stevens, Sandra Day O'Connor, Anthony M. Kennedy, Ruth Bader Ginsburg and Steven G. Breyer, in addition to Souter -- should have blocked ATS suits altogether, because Congress never passed a law specifically authorizing them.

"For over two decades now, unelected federal judges have been usurping this lawmaking power by converting what they regard as norms of international law into American law," Scalia wrote. "Today's opinion approves that process in principle, though urging the lower courts to be more restrained."

The court, Scalia added, "wags a finger at the lower courts for going too far, and then . . . invites them to try again."

The consolidated cases decided yesterday are Sosa v. Alvarez-Machain, No. 03-339, and U.S. v. Alvarez-Machain, No. 03-485.