The related but distinct questions concerning the justification of state authority and the moral obligation to obey the law are crucial and enduring questions of political philosophy and legal theory. The question as to how the authority of the state is to be justified has drawn the attention of philosophers of the stature of Hobbes (1588-1679) and Locke (1632-1704), and the question continues to be debated between ‘philosophical anarchists’ and defenders of the possibility of legitimate state authority such as Professor Raz. The question of the moral obligation to obey the law first taxed Socrates (470-399 BC) (as reported in Plato’s Crito), as he debated whether to flee the judgment of death that the state had passed on him. The question of the moral obligation to obey the law has occupied virtually every leading legal philosopher from Finnis and Raz to Dworkin and Greenawalt. The questions in the chapter consider how state authority is to be justified, if at all, and whether there is any general moral obligation to obey the law.