 He practiced law from 1966–1994 in Houma eventually becoming a senior partner of Duval, Funderburk, Sundbery and Lovell, LP.At the age of 31, Duval served as an elected delegate to the 1973 Louisiana Constitutional Convention, where he served on committees for rules of procedure and for the executive branch.In 1994, he assumed his seat of the federal bench having been confirmed by the U.S. Senate on September 28, 1994.