This book is based upon the papers written by a group of leading international scholars on the 'constitution of social democracy', delivered at a conference to celebrate Professor Keith Ewing's scholarly legacy in labour law, constitutional law, human rights and the law of democracy. The chapters explore the development of social democracy and democratic socialism in theory and political practice from a variety of comparative, legal, and disciplinary perspectives. These developments have occurred against a backdrop of fragmenting 'traditional' political parties, declining collective bargaining, concerns about 'juristocracy' and the displacement of popular sovereignty, the emergence of populist political movements, austerity, and fundamental questions about the future of the European project. With this context in mind, this collection considers whether legal norms can and should contribute to the constitution of social democracy. It could not be more timely in addressing these fundamental constitutional questions at the intersection of law, democracy, and political economy.