Five preeminent legal theorists tackle a range of fundamental questions on the nature of the philosophy of criminal law. Their essays explore the extent to which and the ways in which our systems of criminal law can be seen as rational and principled. The essays discuss some of the principles by which, it is often thought, a system of law should be structured, and they ask whether our own systems are genuinely principled or riven by basic contradictions, reflecting deeper political and social conflicts.