William Warren taught at several law schools, including the University of Illinois, before coming to UCLA. After leaving UCLA in 1972 to become Scott Professor of Law at Stanford, he returned to serve as Dean of the UCLA School of Law from 1975 to 1982. For seven years, he guided the school with exceptional judgment, enhancing the school's national reputation, and engendering the collegial spirit that continues today.
An outstanding teacher, Professor Warren thereafter returned to the classroom full time. He received the Rutter Award for Excellence in Teaching in 1984 and the University's Distinguished Teaching Award in 1985. He has been selected as Professor of the Year by several graduating classes.
Professor Warren has devoted much of his career to working, in various capacities, on law reform, including on the California Commercial Code, Uniform Consumer Credit Code, Regulation Z of Truth in Lending Act, California Claim and Delivery Act, California Earnings Protection Act, and others. With Robert Jordan, he has co-authored the Uniform Consumer Credit Code and more recently drafted portions of the revised Uniform Commercial Code. His major academic interests are commercial, consumer, real estate, and bankruptcy law. He has, with Steven Walt, recently authored a new edition of Commercial Law (2007), and with Daniel Bussel, a new edition of Bankruptcy (2006). During his career, he has published articles in the Boston College Law Review; the UCLA Law Review; the University of Chicago Law Review; the Columbia Law Review; the University of Illinois Law Review; the Kansas Law Review; the Michigan Law Review; the Ohio State Law Journal; the Stanford Law Review; the Texas Law Review; the Vanderbilt Law Review; and the Yale Law Journal, among other journals.