State responsibility — For acts of expropriation — Expropriation decree promulgated by Government of El Salvador at behest of United States — Promulgation of decree resulting in expropriation of property belonging to United States citizens — Whether United States Government responsible for taking — Whether United States action a taking under Fifth Amendment to United States Constitution — Requirement that taking be direct and substantial

Relationship of international law and municipal law — Conduct of foreign relations — Justiciability of foreign relations questions — Political question doctrine — Criteria for determining whether doctrine applicable — United States involvement in expropriation of United States citizens’ property by foreign government — Whether raising justiciable questions

Expropriation — Definition — Taking of property — Extinguishment of claim under international law — Whether constituting a taking of property

Expropriation — Taking of property — Responsibility for — Whether United States Government responsible for taking property belonging to United States citizens by foreign government — The law of the United States