Starving Luxembourg? A quantitative study investigating the behaviour of national judges under the preliminary ruling procedure

The preliminary ruling procedure (PRP) is of paramount importance as the engine of the EU legal order. It has been labelled “the most fundamental element in the constitutional architecture” of the EU judicial system. Yet, what drives national judges to refer cases to the CJEU? Despite the significance of that question, surprisingly little is known about the decision of referral, with a lack of comprehensive studies including the cases not sent. Drawing conclusions on the small sample of referred judgments to make insights on the decision generally risk bias. Access to data regarding the practice of Swedish courts provide for a unique opportunity to examine the judicial behavior of national judges in relation to the PRP. The aim of this paper is to study the factors at play behind the decision of referral. This is conducted by testing whether the reasons emphasised in the literature of judicial behaviour at large, and research interviewing judges concerning the PRP specifically, actually accounts for the judges’ general behaviour. Simultaneously, the paper showcase under what conditions a referral is more or less likely. The general theory is structured into three overarching parts. First, there are reasons to believe that institutional factors such as workload, the law, and time constraints affect the decision to refer. Second, factors connected to the individual judge like strategic thinking, level of knowledge and other regarding rationales might impact the decision. Third, case factors such as area of law, salience of the case, the parties and their lawyers might very well be drivers of the decision. The results will provide insights to the questions, for example, of the types of courts that are more or less likely to refer and the characteristics of these judges, the sorts of parties that make a claim for referral, and the types that tend to succeed. In sum, the results will provide valuable insights into the operation of the preliminary ruling procedure – the “jewel in the crown” of the EU legal order.