There is little doubt today that litigation based on EU law has a crucial impact on both constitutional questions regarding the extent of powers conferred on EU institutions and the remaining competences of member states as well as more nuanced issues of policy content. While many of the seminal cases were initiated by private litigants, and subsequent attention has focused on these, the use of litigation has also become commonplace among EU institutions and member state governments, and now represents an essential feature of the EU’s policy cycle. The papers in this panel illustrate how and why the mobilization of EU law has become a regular feature in EU policy making. Rather than merely an issue of enforcing compliance at the end of the cycle, as traditionally envisaged, litigation can constitute an endgame in the legislative procedure, as in annulment proceedings between legislative institutions. It can also be used as a lever to gain access to the legislative process in the first place - a strategy the European Parliament has repeatedly used to its advantage. It can also signal contestation in the implementation stage of policy, where member states disagree with Commission action and decide to take it to court. Finally, the traditional stage of enforcement can be used, particularly by the Commission, to alter the content of policy and to feed back into the policy formulation and the legislative stage. The panel makes a strong case that legal mobilization should form part of standard policy analysis.