The decision of the European Community (EC) members to complete their “internal market” by the end of 1992, as embodied in the 1987 Single European Act (SEA), may represent the most ambitious instance of multilateral cooperation since the construction of the post-World War II international order. The economic objective of internal market completion is the removal of a wide array of nontariff barriers to trade that elsewhere have proved politically intractable, including border controls, national standards, preferential procurement policies, and industrial subsidies. The institutional structures underpinning the internal market are more constraining on the behavior of sovereign states than has been the case for other international regimes. The SEA replaced unanimity voting (national vetoes) in the primary decision-making body of the EC, the Council of Ministers, with a system of majority voting over matters pertaining to the internal market. In addition, the internal market is buttressed by an elaborate and powerful legal system. EC law is considered to have supremacy over national laws and to have “direct effect” in domestic jurisdictions, regardless of whether it is explicitly incorporated through legislation.