Professor Johnson is a hearings officer with the New Hampshire Department of Education. He was previously in private practice with a focus in administrative law, constitutional law, education law, and health law. He was involved in a number of precedent setting cases including Claremont v. Governor, the case establishing that all New Hampshire students have a constitutional right to an adequate education. He is a member of the United States Supreme Court Bar. Professor Johnson is the author of a number of articles and books in various areas of law, including two casebooks in the education law area.