Through its rulings, the Court of Justice of the European Union (CJEU) has transformed ambiguous Treaty articles into specific rules that challenge national policy making and further European integration. National courts are said to be of crucial importance for the pace of this legal integration since they are the CJEU’s main case suppliers. The central theoretical debate in this literature therefore revolves around the question of whether or not the national courts are supporting further European legal integration. However, although the role of national courts has been subject to much discussion systematic research of their behavior, beyond the number of cases they refer, is largely absent. In this paper I shed new light on the national courts’ key behavioral pattern by explaining why the national courts express support for either the EU law or the national legislation in the legal cases they send to the CJEU through the preliminary ruling procedure. The empirical analysis builds on a logistic regression analysis of an original dataset consisting of 450 cases referred from the member state courts as well as on in-depth interviews with 20 Swedish judges. The first results show that the highest courts are more likely to express support for the national legislation in their requests for preliminary rulings compared to the lower courts. The courts’ place in the judicial hierarchy is therefore understood as a factor that influences national courts’ support for further legal integration.
