This book aims to extend the current research and debate in constitutional economics by using a positive economics approach. Born out of discontent with the current state in constitutional economics, this book presents an inquiry in the possibilities of a positive constitutional economics, and how societies choose their constitutional rules. Drawing on economics, the book examines the emergence of constitutions and how and why they change over time. The author proposes that model constitutions are based on, and backed by institutions which have developed spontaneously. He presents some predictions on the scope of constitutional change under various constitutional settings and factors which cause constitutional change. Stefan Voigt concludes that constitutional change is reconceptualized as the outcome of a bargaining game, in which changes reflect the altered bargaining power of the actors. This book will be welcomed by academics working in the fields of political economy, law and economics as well as those from the public choice and new institutional schools of thought.