Donald H. Regan, the William W. Bishop Jr. Collegiate Professor of Law, is also a professor of philosophy at the University of Michigan. He teaches and writes about international trade law, particularly the impact of trade law on national health, safety, and environmental regulation; on moral and political philosophy, with a special interest in the theory of the good; and on constitutional law, concentrating on federalism issues.

Professor Regan has been a member of the American Academy of Arts and Sciences since 1998, and has been a Guggenheim Fellow, a fellow at the National Center for the Humanities, and a visiting fellow at All Souls College, Oxford. His book, Utilitarianism and Co-operation, shared the Franklin J. Matchette Prize of the American Philosophical Association for 1979–1980. Professor Regan began his academic teaching career at Michigan in 1968. He has visited at the University of California, Berkeley, the University of Virginia, and the University of Zagreb. Currently, he teaches a seminar on the philosophy of free trade in the master's program in Law in a European and Global Context at the Catholic University of Portugal (Lisbon). In spring 2019, he was a Fulbright Distinguished Professor at the University of Trento, Italy.