This book brings together contibutions form EU legal scholars interested in processbased approaches to navigating the federal balance of competences within the European Union. The book discusses the relationship between the procedral and substantive aspects of judicial review in EU law, and offers a comparative perspective on these matters, using the US and the ECHR systems as examples. In so doing, the contibutions in this book also analyse the scope of application and limits of the theory of process-oriented federalism in EU law. With procedural dimensions to WU law constantly growing, thisbook seeks to develop doctrinal and theoretical frameworks which help to explain and comprehend this evolution, thus filling a gap in EU legal research.