Political authority is more than brute power insofar as it is rooted within the institution of a legal order. As social constructs, however, institutions may lack legitimacy. This book suggests a normatively individualistic and functional conception of legitimacy. On this account, political authority can be legitimate because its function, administering peaceful coexistence in a state, allows for all individuals to benefit. For a regime to be legitimate, however, individuals must also be protected against governmental overreach by means of liberal fundamental rights and the rule of law. Although the functional approach does not envision any ideal state, it provides guidelines for designing and reforming constitutions.