 European integration began in 1950, when six states formed the European Coal and Steel Community in the Treaty of Paris. The community established joint international authority over the coal and steel industries of these six countries, entailing executive control through a permanent bureaucracy and a decision-making Council of Ministers composed of foreign ministers of each state. This same model was expanded to a general economic zone in the Treaty of Rome in 1957. It was enhanced by a judicial body, the European Court of Justice, and a legislature, the European Parliament, a directly elected Europe-wide body. Over time, European integration has widened, as the institution now consists of twenty-seven members, and deepened, as it did in the 1991 Maastricht Treaty, which expanded the institution’s powers and reconfigured it as the European Union. Far from a replacement for states, the European Union rather “pools” important aspects of their sovereignty into a “supranational” institution in which their freedom of action is constrained (Keohane &amp; Hoffman 1991). They are no longer absolutely sovereign. In recent years, European integration has continued to advance in important respects. On December 1, 2009, the Treaty of Lisbon came into full force, pooling sovereignty further by strengthening the Council of Ministers and the European Parliament, creating a High Representative of the Union for Foreign Affairs and Security Policy to represent a unified European Union position, and making the European Union’s Charter of Fundamental Human Rights legally binding. However, strains on European integration have emerged in recent years as well. A treaty establishing a Constitution for Europe was signed by the European Union’s member states in 2004, but referendums in France and the Netherlands in 2005 rejected it and prevented its ratification. Then, in 2016, a referendum in the United Kingdom resulted in a victory for the U.K.’s withdrawal from the European Union, popularly known as “Brexit.” 