Sovereignty is a topic on which much has been written already and undoubtedly, more will follow. Writing a book on such a topic is tricky—much has been said already, after all. It is my hope and belief that this book manages to offer something new nonetheless. More specifically, it is my hope and belief that this book manages to offer a conceptual framework for sovereignty which can help academics, practitioners, politicians, journalists, and anyone else interested in the topic of sovereignty make sense of the varied landscape. In some ways, writing a book is a solitary exercise. In other ways, it very much isn’t. Many people at Maastricht University’s Faculty of Law contributed by giving me the time and space for the solitary parts of writing this book and their support, feedback, and company—the less solitary bits. In particular, I want to thank Jaap Hage for a long list of things, including but not limited to frequent discussions on various points of legal theory and for his continued support. This book has benefitted from our ongoing conversation about many topics, and I have learned (and continue to learn) a great deal from him. Aalt-Willem Heringa has often provided a more practically oriented counterpart to theoretical flights of fancy and has my thanks for this and for the continued cooperation between us. Torben Spaak and the Faculty of Law of Stockholm University have welcomed me for a research visit that helped this book along; the Science Committee of the Faculty of Law of Maastricht University helped make that visit possible. Torben Spaak also offered feedback and fruitful discussions on many sections of this book. This book further benefitted from feedback from a number of people, including Andrew Halpin, Jan Smits, Jure Vidmar, Bruno de Witte, and Bert van Roermund. They all have my gratitude. Last but certainly not least, I would like to thank my parents, Elisabeth and Ernst, and my colleagues and friends.