Treaties — Effect in municipal law — Priority of treaty provisions over conflicting provisions of municipal law — EEC Treaty, 1957, Article 12 — Ban on introduction of import duties or equivalent taxes — Primacy of EEC law over subsequently enacted conflicting municipal law

Relationship of international law and municipal law — Treaties — Effect in municipal law — EEC Treaty, 1957 — Nature of legal order established by Treaty

Economics, trade and finance — Taxation — EEC Treaty, 1957, Article 12 — Rule banning new import duties or equivalent taxes — Legality of tax on imported milk products — The law of Belgium