The European judicial system is a multi-layered mechanism driven not only by courts, judicial actors and legal logics but also to a large degree by domestic politics and dynamics. In this regard, there is little doubt about the importance of national actors as boosters, shapers, facilitators, enforcing but sometimes also inhibiting legal demands coming from European courts, such as the Court of Justice of the European Union and the European Court of Human Rights. Recently, attempts have been made to clarify how the involvement and strategies of national courts, governments, and civil society affect the decisions and development of the jurisprudence of the European Court of Justice and the European Court of Human Rights. European regional courts are considered a powerful tool to influence national policy (Alter, 2000), and this is why domestic actors and institutions might attempt to use their resources and design strategies to influence or constrain the impact of these Courts. Under this assumption, the panel proposes the following questions: a) what is the role and impact of national courts for the integration of European Law?, b) how do governments litigate at the European Courts?, and c) under which conditions interest groups mobilize these Courts?. This panel deepens into this research agenda by studying and reviewing some aspects of the role and interaction of domestic actors with European Courts using new methodological and empirical evidence.