This article scrutinizes the last ten years of the academic debate on EU citizenship law taking nine fundamental disagreements among scholars as starting points. It explores EU citizenship's relationship with three groups of issues of fundamental importance, including the place of this concept within the fabric of EU law, the influence of this concept on the essence of the Union as a system of multi-level governance, and its impact on the lives of ordinary Europeans. A large number of key works which influenced the Court and the legislator in the recent years is assessed to outline the likely direction of future research, as well as EU citizenship's future development. Although the literature on the subject is overwhelmingly rich and diverse, this article aspires to provide a representative sample of issues of interest for the framing of the concept at issue from a supranational perspective, necessarily leaving national literatures aside.

On 4 March 2010 the Court of Justice of the European Union issued its first judgment on the conformity with EU law of national provisions implementing Directive 2003/86/EC on the right to family reunification. In the case Chakroun v. Minister van Buitenlandse Zaken the Court had to rule on the Dutch implementing measures concerning resource requirements and the concepts of family reunification and family formation.

On 21 January 2009 the Belgian Constitutional Court terminated a long-lasting dispute over the conditions for affiliation to the care insurance scheme established by the Flemish Community. What started out as a classical conflict over the division of competences in Belgium resulted in a discussion about the impact of European Community (EC) law on the constitutional autonomy of the member states. Despite the entanglement between Belgian constitutional law and EC law, the Flemish care insurance case reveals the different perspectives of both legal orders. In this case, the dialogue between the Belgian Constitutional Court and the European Court of Justice (ECJ) through the preliminary ruling procedure could not prevent reverse discrimination.

European Court of Justice decision of 25 July 2008, Case C-127/08, Metock et al. v. Minister for Justice, Equality and Law Reform – EU citizens and their third-country family members – ECJ largely reverses Akrich case-law – Dividing line between national and Community competences on immigration – ‘Reverse discrimination’ not a matter of concern for Community law – Analysis of repercussions of decision on EU and national legal orders