“United in Diversity” – The Integration of Enhanced Cooperation into the European Constitutional Order

The “unity dogma” has long characterized the European law discourse. In many of its landmark decisions the European Court of Justice had recourse to the “unity argument,” such as in Costa vs. E.N.E.L. , where it rightly states that “the executive force of Community law cannot vary from one state to another … without jeopardizing the attainment of the objectives of the Treaty.” Other expressions of the “unity dogma” include the legal principle of non-discrimination enshrined in the fundamental freedoms, which lie at the heart of the single market, or the political concept of acquis communautaire obliging new Member States to subscribe to all existing Community laws. Indeed, the establishment of a supranational legal order requires a continued focus on its uniform application in the Member States without which the effectiveness of European law is at stake. My intention is not to call into question the underlying rationale of this quest for unity. The aim of this contribution is rather to show that the asymmetric non-participation of individual Member States in selected areas of Union activity can be embedded into the existing European legal order and does not contradict its constitutional aspirations, thereby giving substance to the Union's motto “United in Diversity.”