State immunity — Jurisdictional immunity — Restrictive theory of immunity — Individual acting in official capacity on behalf of government — Whether entitled to sovereign immunity — Allegation that law enforcement officers of foreign State acting illegally whilst carrying out official duties — Whether depriving officials of immunity — United States Foreign Sovereign Immunities Act 1976

Relationship of international law and municipal law — Act of State and justiciability — United States act of State doctrine — Applicability — United States court barred from questioning validity of act of foreign State within its own jurisdiction — Allegation that British law enforcement officers acting illegally during the course of extradition proceedings — Whether act of State doctrine applicable — The law of the United States