ABSTRACT
The Union and Member States form parallel sources of legal authority, each expressing jurisdictional independence, while recognising the jurisdiction of the ‘other’ order, the Union where Member States are concerned and domestic constitutions where the Union is concerned. Where jurisdictional claims by Union or domestic courts are uncertain, or have constitutional implications for the opposing order, competing claims of legal sovereignty may arise. In this regard, given the Treaties’ temporally unlimited commitment to an array of social, economic and political objectives, domestic legal orders are variously co-opted, reconfigured and challenged by Union legislative and judicial practices. The Court of Justice must ensure these challenges do not lead to constitutional crises in either order, given the Union, as a derivative jurisdiction, remains dependent on the co-operation of domestic institutions. These themes, introduced in Chapters 3 and 4, are developed in this chapter, which examines the constitutional implications of co-existing yet independent, Union and Member State, legal jurisdictions.
