The book proposes a new approach to constitutional analysis of the EU and its legal framework, arguing that the existence of constitutional rights norms within EU law enables this particular legal order to respond effectively to societal and political challenges within the rigidity of constitutionalism. Providing new perspectives on constitutionalism in the EU, this book considers the way the Court of Justice of the European Union (CJEU) discusses and applies the EU citizenship Treaty norms by analysing the courts approach to decision making, which resembles the balancing and weighing of conflicting principles.