James L. Hoover joined Columbia Law School as an assistant law librarian in 1978, a role in which he served until 1981, at which time he became a law librarian and a professor of law. Hoover was a professor of law at Columbia Law School until 2002. During his time at the Law School, he also served as an associate dean from 1981 to 1995 and as a vice dean for administration from 2000 to 2002.
Prior to joining the Law School, Hoover was an associate law librarian and assistant professor of legal bibliography at the University of Oklahoma from 1975 to 1978. From 1974 to 1975, he was an assistant law librarian and assistant professor of legal research at St. Louis University.
Hoover was admitted to the Missouri Bar in 1975. He has been a member of the American Bar Association, as well as the Association of American Law Schools, where he served on the Membership Review Committee.