Born in Tacoma, Washington, Tanner was in the United States Army during World War II, from 1943 to 1945.
He worked as a longshoreman in Tacoma until his graduation from law school.
[1][2] On January 20, 1978, Tanner was nominated by President Jimmy Carter to a joint seat on the United States District Court for the Eastern District of Washington and the United States District Court for the Western District of Washington, vacated by Judge William Nelson Goodwin.
Tanner was confirmed by the United States Senate on May 17, 1978, and received his commission on May 19, 1978, becoming the first black federal judge in the northwest United States.
On November 8, 1978, Tanner was reassigned to the Western District alone.