The immunity of foreign states, their instrumentalities and officials is governed in the United States, in large part, by the Foreign Sovereign Immunities Act, 28 USC §1330. The Act establishes when United States court may exercise subject matter jurisdiction over claims of sovereign immunity.
A practical consideration is also the weight that the Executive in exercising its powers over foreign relations give to claims of immunity of foreign entities and persons. The State Department's practice of offering courts a "Suggestion of Immunity" to express its views came under review by the United States Court of Appeals for the Tenth Circuit in the matter Habyarimana v. Kagame, docket number 11-6315.
On October 10, 2012, the court confirmed the long-practiced tradition of such evaluations and the conclusive effect they may have, in a matter involving a suit under the Alien Torts Claims Act, 28 USC §1350, the Torture Act, 18 USC §2340A and the Racketeeer Influenced and Corrupt Organization Act, 18 USC §1962 filed by widows of two former presidents against the current president of Rwanda whom they consider responsible for their husbands' assassinations. -- Clemens Kochinke, partner, Berliner, Corcoran & Rowe LLP, Washington, DC.