The grounds for debate on fundamental rights in the European Union are currently more fruitful than ever. Following the entry into force of the Lisbon Treaty, not only did the EU avail itself with its own 'Bill of Rights, ' i.e., the Charter of Fundamental Rights of the European Union, but is also preparing for its accession to the European Convention on Human Rights. The frequent horizontal effect of fundamental rights in recent case law of the Court of Justice of the EU is an indication of a stronger presence and the increased significance of fundamental rights in the EU's legal order. The Court of Justice strives to interpret and apply the law in a way which contributes to a build-up of a coherent case law and conforms to fundamental rights as closely as possible. Besides powerfully serving to enhance the inner coherence and consistency of EU law and offering feasible solutions to legal problems, the horizontal application of fundamental rights implies a move towards a strengthened constitutional phase of the integration process. Arguments on fundamental rights entail much more than just formal or dogmatic disputes over the scope of application of an act of EU law. They touch on fundamental questions relating to the functioning of the EU and its constitutional nature which pertains to the entire legal order of the EU. *** Librarians: ebook available Subject: EU Law, Human Rights Law, Constitutional Law