Relationship of international law and municipal law — Jus cogens — Crimes against humanity — Action for damages against Federal Republic of Germany by victim of Holocaust — Whether violation of jus cogens precludes State from relying on sovereign immunity — Whether constitutes implicit waiver of immunity

State immunity — Jurisdictional immunity — Action for damages against Federal Republic of Germany by victim of Holocaust — Plaintiff a United States citizen at time of Holocaust — Whether State immunity applicable — Foreign Sovereign Immunities Act 1976 — Whether having retroactive effect — Commercial activity exception — Requirement of direct effect — Waiver of immunity — Whether violation of jus cogens constitutes implicit waiver — International agreement exception to immunity — Whether international agreement vests individual with private right of action

War and armed conflict — Implementation of the laws of war — Compensation for violations of laws of war — Action by victim of violation against belligerent State in national courts of rival belligerent after conclusion of war — Whether barred by sovereign immunity — Hague Convention No. IV, 1907, Article 3 — Hague Regulations on Land Warfare, 1907, Article 52 — Second World War — Employment of slave labour — The law of the United States