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A Christmas Carol on Differentiated Integration


Differentiated integration has often been criticised for being a challenge to the political unity in the European Union (EU) – in a nutshell, humbug! While the uniformity characterising the acquis communautaireno longer seems to work in the current diversified EU, differentiated integration, which results from the fact that a specific group of Member States is not subject to the same rules as the others, has increasingly become the key to unsolvable deadlocks in EU politics (e.g., Tekin and Wessels 2008). Despite some icy critical reception, differentiation has turned into a viable means for compensating for heterogeneity among Member States in the EU (Tekin 2017: 3).

In order to renew in a Christmassy spirit the fading faith in the effectiveness of differentiated integration and outline its benefits to maintain political unity in the EU, let us take a closer look andtogether visit this phenomenon’s past, present and future!

Let us start by going back to 1993, the year of the Treaty of Maastricht, which by officially launching the European Monetary Union (EMU) marks aconstitutional moment of differentiated integration. Besides the opt-outs from the EMU that Denmark, Ireland and the United Kingdom secured for themselves as a consequence of their strong national identities and Euroscepticism (Schimmelfennig et al. 2015: 777; Tekin 2012), other forms of differentiation also started to emerge as a result of the enlargement rounds of 2004 and 2007. In view of the widening of the EU towards East Central Europe in 2004, old and new members negotiated transitional periods, during which the latter would not yet enjoy the full benefits of EU membership with regard to agricultural subsidies, the Eurozone or the Schengen area (Schimmelfennig and Winzen 2017). With the entry into force of the Treaty of Lisbon in 2009, another milestone in the history of differentiation was set. This Treaty continued to write out the EU’s official motto in varietate concordia, i.e.,“united in diversity”. Throughout the years, differentiated integration thus kept being a favoured solution to political impasses and difficulties attached to the EU’s intrinsic diversity. The EU did not collapse under the weight of national resentments and the solution of a multi-speed Europe – in which a smaller group of both able and willing Member States proceeds with integration, while the other Member States will follow as soon as their ability corresponds to the commonly defined objectives (Tekin 2012: 42) – made it possible to avoid a Europe à la carte as well as its inherent risk of fragmentation.

Revisiting the present situation of the EU, crisis management without differentiated integration seems to be a nearly impossible endeavour. Flexible solutions of integration, such as a multi-speed Europe during the so-called “big bang” enlargement or variable geometries to enhance cooperation in the Common Security and Defence Policy (CSDP), can have positive effects on the overall political unity among EU Member States. Today, the EU is increasingly working towards using procedures for differentiated integration defined in the Treaties, such as the Permanent Structured Cooperation on security and defence, in short PESCO (Art. 42 and 46 TEU), which pursues within the CSDP further structural integration in defence matters and has a legally binding nature on participating Member States.The EU Treaties have envisaged a process of enhanced cooperation ever since the Treaty of Amsterdam (1999). So far, besides PESCO, four other forms of enhanced cooperation have been agreed upon: international divorce law (2010); a European Unitary Patent (2011); Property Regime Rules (2016); and a European Public Prosecutor (2017) (European Commission 2019; see also Tekin 2017). At the same time, however, the EU is struggling with new disruptive challenges such as national backlashes in multiple Member States, the 2016 Brexit vote, which triggered a heated debate on disintegration, as well as the reminiscence of the 2015–16 Schengen crisis, which laid bare a dysfunctional asylum system as well as solidarity problems among EU Member States. The EU’s successful integration achievements as well as its challenges, given the subsequent Treaty revisions, enlargement rounds and crises, have also determined a specific cyclicality in the discourse on differentiated integration. The ubiquitous narrative on “united in diversity”, which acknowledges the heterogeneity among Member States, has accordingly changed in response to the historical developments of EU integration. Whereas during the enlargement negotiations, institutional figures and political leaders championed the idea of maintaining the EU’s unity despite its intrinsic political differentiation, new narratives of disenchantment and general discontent have emerged lately with regard to the EU’s diversity, especially after the crises in the Eurozone. Contemporary threats to the EU’s political unity have consequently fuelled a new narrative on “divided in unity”, which epitomizes major cleavages between national leaders and EU representatives, but also internal contradictions among Member States.

Having visited the past and the present, let us finally have a look into the future. An optimist might see an EU five or ten years from now in which differentiation has become the new normal, safeguarding European integration and bringing the EU’s “insiders” and “outsiders”closer. Nonetheless, given a multi-speed EU several criteria need to be satisfied to eventually achieve a positive – not to say jolly – scenario. First, specific policy areas and common values should not be compromised, e.g.,the rule of law, democracy, or human rights (Art. 2 TEU); second, differentiated solutions should be incrementally transferred to the secondary law level rather than to the primary law level; third, forms of differentiated integration should not undermine the EU as a sovereign global actor speaking with a single voice. By acknowledging the EU’s heterogeneity and diversity, forms of differentiated integration will be able to address current challenges more effectively and make the Union more resilient and accountable to citizens.

After this brief time travel we conclude that one cannot exclaim “humbug” concerning differentiated integration as long as it is compatible with the core principles of the EU, sustainable in terms of governance and acceptable to EU citizens, Member States and involved third partners.



European Commission, Scenario 3 of the White Paper on the Future of Europe: Those Who Want More Do More, 2019,

F. Schimmelfennig, D.Leuffen and B. Rittberger, “The European Union as a System of Differentiated Integration: Interdependence, Politicization and Differentiation”, in Journal of European Public Policy, Vol. 22 (2015), 764-782

F. Schimmelfennig and T. Winzen, “Eastern Enlargement and Differentiated Integration: Towards Normalization”, Journal of European Public Policy, Vol. 24 (2017), p. 239-258

F. Tekin, Differentiated Integration at Work: The Institutionalisation and Implementation of Opt-Outs from European Integration in the Area of Freedom, Security and Justice, Baden-Baden, Nomos, 2012

F. Tekin, “Differentiated Integration”, in IEP Online Papers, 2017,

F. Tekin and W. Wessels, “Flexibility within the Lisbon Treaty: Trademark or Empty Promise?”, in EIPAscope, Vol. 1 (2008), p. 25-31

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