This volume collects some of the best recent writings on St. Thomas's philosophy of law and includes a critical examination of Aquinas's theory of the relation between law and morality, his natural law theory, as well as the modern reformulation of his approach to natural rights. The volume shows how Aquinas understood the importance of positive law and demonstrates the modern relevance of his writings by including Thomistic critiques of modern jurisprudence and examples of applications of Thomistic jurisprudence to specific modern legal problems such as federalism, environmental policy, abortion and euthanasia. The volume also features an introduction which places Aquinas's writings in the context of modern jurisprudence as well as an extensive bibliography. The volume is suited to the needs of jurisprudence scholars, teachers and students and is an essential resource for all law libraries.