Robert Nagel joined the faculty of the University of Colorado School of Law in 1975, leaving a position as a deputy attorney general in Pennsylvania. Since then, he has focused on constitutional law and theory. For an audience of legal scholars, Nagel has written prolifically, including four books and over 50 law review articles.

However, he also has contributed to the popular debate on constitutional issues, including free speech, hate codes and federalism, by addressing his ideas to the general citizenry in articles and opinion pieces in publications such as The New Republic, the Wall Street Journal, First Things and Washington Monthly. Much of his work has focused on the relationship between the judiciary (and its interpretation of the Constitution) and the wider context of American political culture.

His two earlier books on this topic, Constitutional Cultures: The Mentality and Consequences of Judicial Review and Judicial Power and American Character: Censoring Ourselves in an Anxious Age, were widely read and reviewed. He recently completed The Implosion of American Federalism, a book on the cultural and constitutional ramifications of political centralization.

Nagel has testified before several congressional committees. He was formerly the director of the Law School's Byron R. White Center for the Study of American Constitutional Law. In 2003 he was elected a Fellow of the American Academy of Arts and Sciences.

He received his bachelor's degree with high honors, Phi Beta Kappa, from Swarthmore College and earned his law degree at Yale.