Up until the Treaty of Maastricht, there was a growing sense of the unity of a single integrated Community legal order. However, times have changed and the contours of EU legal order have become rather fuzzy. Bruno de Witte argues that the current complex regime of differentiation is likely to stay, and analyses the reasons for and consequences of this shift to differentiation.

By Bruno De Witte

Up until the Treaty of Maastricht, there was a growing sense of the unity of a single integrated Community legal order despite the existence of three different Communities. That unitary legal order was also uniformly applicable to all the Member States, except for some limited derogations provided by primary or secondary law, which exempted single countries from specific rules of Community law. The Court of Justice set great store on this uniform application.

However, there were also inherent limits to this aspiration at uniform application. The main limit was, and is, that EU law is applied most of the time by national authorities and courts that do not actually apply EU law faithfully and correctly on many occasions. But there was another limit, inherent in Community law itself, namely the fact that there were forms of EU law and policy that contained an inherent permission for differential application. The most obvious example are directives that could be transposed by the Member States in a way which left them free to decide the ‘form and methods’ of their application. Still, those instances of territorially-based differential application of EC law could be seen as anomalies which the further development of the European integration process, and of the Community legal order specifically, would gradually eliminate.

This is, quite clearly, no longer the dominant perception today. Not only is the gap between the goal of uniform application and the messy practice within the Member States now accepted as an unavoidable feature of the multilevel nature of application of EU law, but the EU legal order itself has gradually moved away from the ideal of unity and now accommodates various forms of variable geometry between its Member States, whereby these States are either allowed to derogate from the common norms, or, more radically, where some States are allowed not to participate in the making of EU law norms, and are consequently not bound either to apply such norms.

Strong functional and normative reasons explain this evolution and make it very likely that this complex regime of differentiation is there to stay and (probably) to expand further. The functional reason is that variable geometry has proved essential for allowing European integration to proceed. Widening, deepening and uniformity could not go together. The choice for widening-with-deepening made repeatedly in the past twenty years of the EU’s existence, led to sacrificing the aspiration to the creation of a uniform legal order. But differentiation is also normatively attractive since it allows for the diverse preferences of national governments and national public opinions to be accommodated. Some countries can decide to move ahead with the European integration process without being stopped by the more reluctant countries but also without forcing the latter to participate in new cooperation ventures.

The existence of a controlled system for differentiation between Member States has now become a stable characteristic of EU law. Each of the elements of the flexibility design seems likely to last, and to flourish. First, there is no reason to think that the major opt-out areas, namely EMU, immigration and criminal law, will disappear any time soon; indeed, the United Kingdom government’s wish to renegotiate the terms of the country’s membership of the EU may lead to the further growth and consolidation of the opt-out construction. In addition, now that enhanced cooperation has been experimented a few times, one can expect it to become a regularly used instrument in the EU’s law-making toolbox, in particular in order to circumvent single country veto positions in policy matters where the unanimity rule continues to apply. Thirdly, recourse to international agreements between groups of Member States outside the EU legal framework has been confirmed to be a valid option, particularly through its use in the context of the euro crisis, with the adoption of the ESM treaty, the Fiscal Compact and the Agreement on the Single Resolution Fund. Finally, we might see a continued and increasing use of the omnipresent micro-flexibility that has been part of Community law for decades, namely the recourse to minimum harmonisation, to soft law and to tailor-made derogations.

As a result, the contours of the EU legal order have become rather fuzzy. In principle, there are firm criteria to determine whether a legal norm belongs to the EU legal order or not. Thus, measures of enhanced cooperation are part of EU law, although they are binding only upon, and within, the Member States that participated in their adoption. Similarly, legal measures from which some countries opt out are also part of the EU legal order, despite their limited geographical scope. On the contrary, international agreements concluded by a limited set of Member States (such as the ESM treaty and the Fiscal Compact) are not part of the EU legal order, and the Court of Justice cannot review the decisions adopted by organs set up under such an agreement. However, the institutional practice has led to a number of intertwinements between organs and legal norms of EU law and non-EU law. Examples of this fuzziness are the fact that EU institutions are being ‘borrowed’ by the Member States when setting up and operating an international side regime, as is the case with the European Stability Mechanism; and the fact that the entry into force of norms of secondary EU law is conditioned on the prior entry into force of a satellite agreement, as we have seen in recent years with the unified patent regime and the banking resolution mechanism.


If the formal criteria for deciding what belongs to the EU legal order still function well, the content of that EU legal order presents a very unusual shape. Its degree of fragmentation, in terms of participation of states in decision-making, and of applicability of legal norms across the EU territory, is rather unique and sets the European Union firmly apart from the federal constitutional systems to which it resembles in other respects. The Court’s old ideal of EU legal rules being ‘fully applicable at the same time and with identical effects over the whole territory of the Community’ has become unattainable. This, in itself, may not be such a great loss; but the easy and almost insouciant recourse to flexibility also comes with lack of transparency, complicated accountability mechanisms, and neglect of intra-state solidarity, and those are serious challenges for the constitutional integrity of the European Union. There is thus a danger that the mechanisms of differentiation, rather than serving as useful instruments of flexibility, may turn into causes of the disintegration of the European Union.

Bruno De witteBruno De Witte (CERiM member) is professor of European Union law at Maastricht University, and part-time professor at the Robert Schuman Centre of the European University Institute (EUI) in Florence. He is co-director of the Maastricht Centre for European Law. For his personal page see here

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