As U.S. Attorney, McAllister is in charge of the U.S. Attorney's Office for the District of Kansas, which comprises approximately 50 Assistant U.S. Attorneys and 50 support staff members working in offices in Topeka, Kansas City, Kan., and Wichita. His main office is in Kansas City, Kan., and he travels frequently to the other offices.

McAllister has served as the Solicitor General of Kansas and the E.S. & Tom W. Hampton Distinguished Professor of Law at the University of Kansas. He argued nine times before the Supreme Court of the United States and he has taught constitutional law and federal civil rights law at KU. He clerked for the Honorable Clarence Thomas and the Honorable Byron R. White of the United States Supreme Court, and the Honorable Richard A. Posner at the United States Court of Appeals for the Seventh Circuit. McAllister received a bachelor's degree in 1985 from the University of Kansas, and a law degree in 1988 from the University of Kansas School of Law.