The authority of European law is a classic question explored in all general textbooks, but the entry into force of the Lisbon Treaty and new cases from several constitutional courts in Europe have reawakened this interest. Addressing the interaction between EEA law and European law, on one hand, and the Icelandic legal system, on the other, and combining the perspectives through the lenses of different European courts is a project requiring in-depth study and meticulous explanation both in Iceland and abroad. This book sets out to explore the current status, scope and limits of the authority of European law as well as the role of national judges in the construction of the EU and EEA legal orders by putting together European and Icelandic perspectives. The aim is to analyse the principle of the primacy of EU law, as construed by the ECJ and different European constitutional courts, on the one hand (Part I), and the EEA principles of consistent interpretation, “quasi-primacy” and State liability, as reflected in the jurisprudence of the EFTA Court and the Icelandic courts, on the other (Part II). The intention of the authors is to draw on the different existing perspectives to provide a richer, fuller, and more integrated picture of a complex topic which is the interaction of European law and national laws in the EU legal order and its parallel development in EEA law and, more specifically, in Iceland. This book is an invitation for all actors to get acquainted with the most recent legal knowledge and theories in the fields of EU and EEA law, stand up to the challenges ahead and find the proper way to assure a more constructive relationship between the European legal system and domestic law.