Legal integration and use of the preliminary ruling process in the European Union

Scholars agree that the preliminary ruling system of the European Court of Justice has been instrumental in promoting European integration; however, no consensus has been reached as to why the system is used. Although many explanations have been posited, there has been no systematic comparative test among them to date. In this article, we perform this test. We find evidence that transnational economic activity, public support for integration, monist or dualist tradition, judicial review, and the public's political awareness influence use of the preliminary ruling system.