The idea of European union is as old as the European idea of the sovereign State. Yet the spectacular rise of the latter overshadowed the idea of European union for centuries. Within the twentieth century, two ruinous world wars and the social forces of globalization, however, discredited the idea of the sovereign State. The decline of the monadic State found expression in the spread of inter-state cooperation. The various efforts at European cooperation after the Second World War indeed formed part of a general transition from an international law of coexistence to an international law of cooperation.

The European Union was born in 1952 with the coming into being of the European Coal and Steel Community (ECSC). Its original members were six European States: Belgium, France, Germany, Italy, Luxembourg, and the Netherlands. The Community had been created to integrate one industrial sector; and the very concept of integration indicated the wish of the contracting States “to break with the ordinary forms of international treaties and organizations”. The 1957 Treaty of Rome created two additional Communities: the European Atomic Energy Community and the European (Economic) Community. The “three Communities” were partly “merged” in 1967, but continued to exist in relative independence. A major organizational leap was taken with the 1992 Maastricht Treaty. It integrated the three Communities into the European Union. But for a decade, this European Union was under constant constitutional construction. In an attempt to prepare the Union for the twenty-first century, a European Convention was charged to draft a Constitutional Treaty in 2001. But this Treaty failed; and it took almost another decade to rescue the reform into the 2007 Reform (Lisbon) Treaty that came into force on 1 December 2009. The Lisbon Treaty has replaced the “old” European Union with the “new” European Union. It is this European Union that will be analysed in this “Introduction to European Law”.