Associate attorney at Foreman, Dyess, Prewett, Rosenberg & Henderson, 1973 to 1980, Walne withdrew from the firm and opened a solo practice focused on oil and gas matters while he co-founded Black Stone Oil Company. In 1989 Mr. Walne joined the Houston office of Johnson & Gibbs. He left that firm to join Looper, Reed Mark & McGraw in 1991, and in 1994 he withdrew in order to re-open his solo practice and later with Robert M. Timby formed Walne & Timby, LLP, where he practiced until he joined Winstead, P.C., in May, 2008. In November, 2010, Mr. Walne again revived his solo practice.