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

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. Such “collateral orders” include orders denying claims of absolute immunity, qualified immunity, and state sovereign immunity. The question presented , which has divided the circuit courts 5 -3, is whether an order denying a government contractor’s claim of derivative sovereign immunity is immediately appealable under the collateral -order doctrine. ii RULE 14.1( B) STATEMENT The parties listed in the caption were