This book demonstrates the limits of constitutionalism in the EU. It explores the ‘twin crises’ - the failure of the Constitutional Treaty in 2005 and the more recent Eurozone crisis - to illuminate both the possibilities and pitfalls of the integration project. It argues that European integration overburdened law in an attempt to overcome deep-seated political deficiencies. It further contends that the EU shifted from an unsuccessful attempt at democratisation via politicisation (the Constitutional Treaty), to an unintended politicisation without democratisation (the Eurozone crisis) only a few years later. The book makes the case that this course is unsustainable and threatens the goal of European unity. This text will be of key interest to students and scholars in the fields of EU studies, EU law, democracy studies, constitutional studies and international relations.