William Howell, an associate professor in the Harris School of Public Policy at the University of Chicago, has written widely on separation-of-powers issues and American political institutions, especially the presidency. His recent research examines how domestic political institutions constrain the president's ability to exercise military force abroad. Before joining the Harris School, he taught in the government department at Harvard University and the political science department at the University of Wisconsin. In 2000, he received a Ph.D. in political science from Stanford University.