Born in Marion, North Carolina, Erwin served in the United States Army during World War II, from 1943 to 1946, achieving the rank of Sergeant.
Erwin served on his local school board in Winston-Salem from 1961 to 1968, on the North Carolina State Board of Education from 1971 to 1977, and was elected to two terms in the North Carolina Senate as a Democrat.
In 1977, Governor Jim Hunt appointed him to the North Carolina Court of Appeals.
[1] On June 11, 1980, Erwin was nominated by President Jimmy Carter to a new seat on the United States District Court for the Middle District of North Carolina created by 92 Stat.
Erwin served as Chief Judge from 1988 until he assumed senior status on September 22, 1992.