When the European Communities were established, the European Court of Justice was composed of a handful of judges and staff members, there was very little European law to interpret, and few national courts actively participated in the community legal system. In the decades since, the scope of European law has expanded dramatically, the Court of Justice itself has grown into a much larger institution and the network of national courts that cooperate (and sometimes conflict) with the European Court in the interpretation and application of EU law has burgeoned. Today thousands of judges across twenty-seven member states are trained in European law, participate in EU-related judicial networks and engage with the EU courts in Luxembourg. This panel brings together scholars of European legal integration and multi-level governance to explore the construction of this multi-level legal system and the interactions between the national and EU level courts and the governments that comprise it.