 Born in Philadelphia, Corbett is a graduate of Lebanon Valley College and St. Mary's University School of Law and served as a captain in the Pennsylvania Army National Guard.Corbett began his career as an assistant district attorney in Allegheny County, Pennsylvania in 1976.Corbett then joined the U.S. Department of Justice as an assistant U.S. Attorney for the Western District of Pennsylvania, serving from 1980 to 1983, upon entering private practice.