State succession — Rights and obligations — Single State succeeded by several States — Germany — German Democratic Republic and Federal Republic of Germany as successors to German Reich — Scope and nature of acquired rights and obligations — Whether limited to rights and obligations within territorial jurisdiction of each successor State — Right of German Democratic Republic to claim for valuable painting belonging to German Reich — Refusal by German Democratic Republic to recognize obligations of German Reich — Whether precluding enforcement of rights in the United States courts — Doctrine of unjust enrichment

Recognition — States — Effects of recognition and non-recognition — Effects in law of recognizing State — German Democratic Republic — Non-recognition by the United States — Whether non-recognition suspending application of limitation period under New York Statute of Limitations — Subsequent recognition by United States — Effect upon right of access to municipal courts

Relationship of international law and municipal law — Conduct of foreign relations — Recognition of States — Conclusiveness of recognition by the Executive — Recognition including right of access to municipal courts — Whether courts having power to withhold right of access — Political question doctrine

States — Continuity of States — Germany — Status of Germany after 1945 — Whether Federal Republic of Germany sole successor to German Reich — Constitution of Federal Republic of Germany — Whether precluding German Democratic Republic from claiming as successor to German Reich

War and armed conflict — Occupation of territory — Nature and effect of occupation — Effect on sovereignty — Status of laws enacted by prior sovereign — German Reich — Occupation by Allied Powers — Territory in Eastern Germany temporarily administered by United States Military Government — Territory subsequently becoming part of Soviet Zone of Occupation — Status of laws enacted by German Reich — Status of laws promulgated by United States and Soviet Military Governments

Relationship of international law and municipal law — Act of State doctrine and justiciability — Commercial activity exception — Repudiation of contractual obligations by State legislature — Whether a commercial activity — Principle that United States court will not question the validity of expropriation by foreign State of property within that State's territory — Situs of property — Obligation by State to pay annuity to descendants of former sovereign

Expropriation — Debt — Situs of debt — Obligation by German Democratic Republic to pay annuity to descendants of former sovereign — Whether obligation sited in the German Democratic Republic

State immunity — Jurisdictional immunity — Counterclaim exception — Requirement that counterclaim arising out of the subject matter of claim by foreign State — Claim by instrumentality of German Democratic Republic for paintings — Cross-claim against German Democratic Republic for non-payment of contractual obligations — Whether within counterclaim exception — United States Foreign Sovereign Immunities Act 1976

Sources of international law — General principles of law — Doctrine of unjust enrichment — Applicability to dispute concerning State succession to property rights — The law of the United States