Power tends to be abused. Based on this realization, the democratic constitutional state establishes a complex system of power distribution and limitation: the rule of law, separation of powers, a constitution with justiciable priority, and democratic controls make it a successful model that protects citizens from oppression and arbitrariness to an unprecedented extent. But does it also have a future? This book presents the development and fundamental elements of the democratic constitutional state in a compact form and outlines the most important new challenges.