Whether an order denying a federal contractor's claim of derivative sovereign immunity is an immediately appealable final order under the collateral-order doctrine

QUESTION PRESENTED Under 28 U.S.C. § 1291, the courts of appeals “have jurisdiction of appeals from all final decisions of the district courts.” This Court has held that certain orders are immediately appealable under Section 1291 even though they do not terminate the litigation. These “collateral orders” include orders denying claims of absolute immunity, qualified immunity, and state sovereign immunity. In this case, the court of appeals dismissed petitioner’s appeal of a ruling denying its claim of derivative sovereign immunity, which petitioner invoked in response to allegations that its employees—civilian contractors working as interrogators with the U.S. military—violated the Alien Tort Statute by conspiring with, or aiding and abetting, the U.S. military in the mistreatment of Iraqi detainees. According to the district court, petitioner is not entitled to derivative sovereign immunity because the United States has purportedly waived, by implication, its immunity for violations of jus cogens norms of international law. The court of appeals held that the district court’s immunity ruling was nonfinal and therefore not within its jurisdiction under Section 1291. The question presented is whether an order denying a federal contractor’s claim of derivative sovereign immunity is an immediately appealable final order under the collateral-order doctrine.