He was a law clerk to Judge Harold Montelle Stephens of the United States Court of Appeals for the District of Columbia Circuit from 1939 to 1940, and was in private practice in Los Angeles from 1940 to 1941.
He served in the United States Army during World War II, from 1941 to 1945, achieving the rank of lieutenant colonel.
After the war, he returned to private practice in Los Angeles from 1945 to 1966, also serving as a special assistant to the United States Attorney General from 1958 to 1964.
Gray was confirmed by the United States Senate on June 29, 1966, and received his commission on July 2, 1966.
He assumed senior status on March 26, 1982, serving in that capacity until his death on February 10, 1992, in Pasadena, California.