Differentiation has become the new normal in the European Union (EU) and one of the most crucial matters in defining its future. A certain degree of differentiation has always been part of the European integration project since its early days. The Eurozone and the Schengen area have further consolidated this trend into long-term projects of differentiated integration among EU Member States.

A number of unprecedented internal and external challenges to the EU, however, including the financial and economic crisis, the migration phenomenon, renewed geopolitical tensions and Brexit, have reinforced today the belief that more flexibility is needed within the complex EU machinery. A Permanent Structured Cooperation, for example, has been launched in the field of defence, enabling groups of willing and able Member States to join forces through new, flexible arrangements. Differentiation could offer a way forward also in many other key policy fields within the Union, where uniformity is undesirable or unattainable, as well as in the design of EU external action within an increasingly unstable global environment, offering manifold models of cooperation between the EU and candidate countries, potential accession countries and associated third countries.

EU IDEA’s key goal is to address whetherhow much and what form of differentiation is not only compatible with, but is also conducive to a more effective, cohesive and democratic EU. The basic claim of the project is that differentiation is not only necessary to address current challenges more effectively, by making the Union more resilient and responsive to citizens. Differentiation is also desirable as long as such flexibility is compatible with the core principles of the EU’s constitutionalism and identity, sustainable in terms of governance, and acceptable to EU citizens, Member States and affected third partners.