Begining his legal career as law clerk to Judge Walter F. George, Hooper became close friends with Richard B. Russell while Russell was Speaker of the Georgia House. As Governor, Russell appointed Hooper to the Georgia Court of Appeals. Follow a 9-year stint as a teacher at Atlanta Law School and serving as Superior Court Justice of the Atlanta District, in 1949 Hooper was appointed to the U. S. District Court.

He played pivotal roles in the integration of Atlanta city schools, the integration of the University of Georgia and ordered future governor Lester Maddox to seat African-Americans at Pickwick Restaurant. Maddox closed the restaurant rather than be forced to integrate.