ABSTRACT
Introduction The concept of ‘closer co-operation’, introduced in the revised version of the Maastricht Treaty at the Amsterdam summit of July 1997, echoes the more informal one of ‘hard core’: indeed, it allows some member countries of the European Union (EU) to go further on the road of European integration without being hindered by the other partners. The insertion of this provision in the treaty followed a debate engaged on the German side as early as 1994 and later joined by Paris: Chancellor Kohl and French President Chirac sent two joint letters to the then presidents of the European Council, in December 1995 and October 1996, proposing the introduction of such a clause. Indeed, France and Germany share the idea that, in an enlarged EU, it will be increasingly difficult to take decisions by the unanimity rule, especially in fields where the notions of national interests and sovereignty are at stake: this is particularly true in the context of Common Foreign and Security Policy (CFSP).
