The Legitimacy of European Constitutional Orders is a systematic and comparative study of European constitutional orders, taking into consideration the national constitutional traditions of European countries, as well as the defining power of EU law. Drawing on a wealth of case studies, this book explores the trajectories followed by European national constitutional orders in their efforts to attain legitimacy. More in particular, the book investigates Bruce Ackerman’s influential world constitutionalism project and engages with the three legitimacy pathways put forward therein; that is, the revolutionary, the establishment, and the elite pathways. Such ideal trajectories are revisited and found in need of being questioned so as to furnish the conceptual tools essential in the efforts of reconstructing and assessing the European constitutional orders. The book also considers the relevance of constitutional transformation and change in comparative constitutional law, and accounts for the manifold impacts of the European integration process on national constitutional trajectories. Offering an original perspective on the issue of constitutional legitimacy in the European context, this comprehensive book will be of interest to scholars and students of comparative law, constitutional law, European law, political science and constitutional theory as well as researchers and practitioners in these fields.