In Etat Belge v. S.A. "Fromagerie Franco-Suisse Le Ski," the Supreme Court of Belgium was faced with a conflict between a provision of the European Economic Community (EEC) treaty and a domestic law enacted subsequent to Belgian ratification of the treaty. The traditional approach in Belgium--and, incidentally, the rule in the United States--had been to give effect to whichever was enacted later in time. Although not stated explicitly in any constitutional provision, this rule had been well settled in Belgium.
Michigan Law Review,
Conflicts Between Treaties and Subsequently Enacted Statutes in Belgium: Etat Belge v. S.A. "Fromagerie Franco-Suisse Le Ski",
Mich. L. Rev.
Available at: https://repository.law.umich.edu/mlr/vol72/iss1/4