Law is one of the most complex, intricate and sophisticated creations of human societies. Modern legal systems regulate almost every aspect of our lives—from individual conduct in our everyday interactions with other individuals to systems of government, commerce and economy, and even relations between nations in the international sphere. It is difficult to imagine human existence in a society without law, and certainly difficult to think of such an existence as anything that would resemble human society as we know it. No wonder, then, that philosophy of law encompasses many topics from myriad perspectives and philosophical concerns. No single volume, even as large as this one, can hope to cover all of the philosophical questions we have about the law and various legal institutions. One aim of this volume is to give readers a sense of how wide ranging the philosophical interest in law is, and how different types of philosophical questions are asked about different aspects of law. Another aim of this book is to demonstrate how philosophical arguments are deployed in contemporary philosophy of law—what is assumed or taken for granted, what is considered problematic and in need of careful examination. The essays in this Companion are not written merely as state-of-the-art reports on particular fields in philosophy of law. The authors present their own views on the topics they discuss, arguing for a particular position they favor. We thought that the best way to introduce readers with different backgrounds to the topics covered in this volume would be to demonstrate how philosophy of law strives to make progress with the issues with which it grapples within a piecemeal and careful examination of the questions that law and legal institutions present. The essays are introductory in nature: they do not presume any prior knowledge of the field, but they also try to advance the ball, making some original contribution to the philosophical debates in their respective areas. The chapters of the Companion are arranged under six headings: theories about the nature of law, legal reasoning and interpretation, theories about particular legal areas (such as criminal law, torts, international law and others), law as a coercive order, the moral obligations we may have toward the law, and rights and equality. These divisions are somewhat arbitrary, of course, and they do not necessarily reflect any differences in philosophical outlooks or methods. As readers will come to realize, philosophy of law is very closely entangled with other philosophical areas, in particular, moral and political philosophy, metaethics, philosophy of action and, in some areas, philosophy of language.