In 1944 he was in combat in World War II, serving in France, Belgium, the Netherlands, and Germany.
From 1954 to 1956 he was a civil advisory and trial attorney in the IRS Regional Counsel's offices in Atlanta, Georgia, and Greensboro, North Carolina.
Shields returned to Tennessee to enter private practice, specializing in tax matters, in Knoxville and Chattanooga from 1956 until 1982.
On November 14, 1981, Shields was appointed to the United States Tax Court by President Ronald Reagan, taking the oath of office on February 5, 1982.
He was interred with military honors in the Bethel Baptist Church Cemetery at Townsend, Tennessee.