Professor Murphy discusses the concepts of closer cooperation and flexibility, which are fairly recent additions to European law and policy. These notions essentially refer to the policies and procedures within the Union whereby some member states undertake certain obligations, or participate with some other member states in certain agreed upon activities, while other member states do not participate, or participate on a different scale or on a different timetable. Explicit reference to the concept of "closer cooperation" in the European Union's constitutive documents, or authorization of it, is recent. Provisions regarding "closer cooperation" appear for the first time in the 1997 Amsterdam Treaty ("AT"). But only three years later these provisions were augmented and restated in a modified form in the Union's most recent constitutive document, the Treaty of Nice, which was agreed to by the fifteen member states of the Union on December 11, 2000 at the conclusion of the Nice Summit.
The Treaty of Nice became effective as an amendment to the TEU on February 1, 2003, upon the ratification by all fifteen member states, according to their respective constitutional or administrative procedures. In June 2001, the Treaty of Nice was rejected by the citizens of the Republic of Ireland, voting in a referendum as provided in the Irish Constitution; but in a second referendum, held in October 2002, the Irish voters approved the Treaty. The inclusion of cooperation provisions in the Treaty of Nice in a form different from those of the AT provides an opportunity to consider these less familiar aspects of European Union law and policy as contained in both instruments.
Daniel T. Murphy, Closer or Enhanced Cooperation: Amsterdam or Nice, 31 Ga. J. Int'l & Comp. L. 265 (2003).