The course provides students with basic knowledge of the EU legal system. It is divided into three parts. The first part includes: an introduction to the historical setting of the European Integration, the description of the institutional structure of the EU, its legal sources and the main features of its decision-making process. It starts with an introduction, which focuses on the integration process through the modification of the treaties and the enlargement. It highlights the peculiarities of the European Union as a legal order and a “community of law”, with respect to the phenomenon of international organization. Then, the European institutional framework is examined, taking into account the relation between the Institutions and the principles guiding their interaction. The toolkit adopted by the Union to overcome the democratic deficit is illustrated, including the decision-making procedures for the adoption of EU acts. Then, the course focuses on the principles which regulate the attribution and the exercise of EU competences and the forms of differentiated application. The hierarchy, features and functioning of EU sources is then introduced and explained in its relations with domestic law. The second part is devoted to the enforcement of EU law vis-à-vis the Union, the Member States, and individuals. The notions of primacy, autonomy and direct effect of EU law are widely investigated, alongside the modalities for the implementation of EU law in national legal orders, in particular in Italy. It also gives an account of the functioning of the judicial system of the EU, focusing on the functions of the European Court of Justice in its dialogue with national judges. The third part is devoted to substantive matters, relating to the protection of fundamental rights and the role of the EU Charter, the European citizenship and freedom of circulation within the EU.