International organizations — Headquarters agreements — United Nations — Agreement between the United States and the United Nations regarding the Headquarters of the United Nations, 1947 — Obligations of the United States — Palestine Liberation Organization (“PLO”) Observer Mission — Whether United States required to permit PLO to maintain office in New York — United States Anti-Terrorism Act 1987 — Whether requiring United States Administration to close PLO office — Whether such requirement would be contrary to the Headquarters Agreement — Intention of Congress in passing the legislation

Relationship of international law and municipal law — Treaties — Effect in municipal law — United States — Treaties part of United States law — Act of Congress potentially in conflict with prior treaty obligations — Interpretation of statute — Presumption that Congress does not intend to legislate in a manner contrary to treaty obligations — United Nations-United States Headquarters Agreement, 1947 — United States Anti-Terrorism Act 1987

Treaties — Application by municipal courts — Interpretation — Practice of government in application of treaty — Importance as indication of interpretation to be accorded to treaty — Effect of treaties in domestic law — The law of the United States