Economics, trade and finance — Export licencing system — Arms sales — Legislative ban on arms sales prejudicing “the interests of the international legal order” — Interests of international legal order requiring States to maintain friendly relations with each other — Proposed sale of submarines by Netherlands corporation to Nationalist Republic of China (Taiwan) — Sale causing serious and prolonged disturbance of the Netherlands relations with the People’s Republic of China — Whether sale prejudicing the interests of the international legal order — Whether interests of international legal order outweighed by necessity to maintain freedom of international trade

Treaties — Effect in municipal law — Aid to interpretation of municipal legislation — Dutch Import and Export Act — Prohibition of arms sale having prejudicial effect on “the interests of the international legal order” — Interpretation of “the interests of the international legal order” under Dutch law — Requirement that States maintain friendly relations with each other — Confirmation of interpretation by reference to international treaties — Charter of the United Nations, 1945 — Vienna Convention on Diplomatic Relations, 1961 — The law of the Netherlands