This book explores the global phenomenon of migration, transplantation, and borrowing of constitutional ideas. It combines conceptual and normative approaches to dissect a phenomenon which has been both praised and maligned in political and academic discourse. The book takes a broad view of the term 'constitutional'. Its contributors are drawn from the fields of comparative constitutional law, EU law, medieval history, political philosophy, international law, private law, and administration of justice. They consider constitutional transplantation as a specific case of the migration of ideas and place it within that broader intellectual framework of the movement of knowledge. The results of the movement of constitutional ideas can be found outside, as well as within, the law, and the implications of such movement go beyond it. The authors examine legal and constitutional systems in Asia, Europe, North and South America, as both sources and recipients of transplantations. The authors analyse, from historical, conceptual, and normative angles, the transplantation of constitutions and constitutional ideas from one state to another, and the role played by cultures and histories in the reception of constitutional provisions and ideas.