He served as Special Assistant to the United States Secretary of Agriculture in 1945.
[1] Cowen served as a Trial Judge of the United States Court of Claims from 1942 to 1943, and from 1945 to 1964.
He served as Chief of the Trial Division of the United States Court of Claims from 1959 to 1964.
[1] Cowen was nominated by President Lyndon B. Johnson on June 16, 1964, to the Chief Judge seat of the United States Court of Claims vacated by Chief Judge John Marvin Jones.
He was reassigned by operation of law to the United States Court of Appeals for the Federal Circuit on October 1, 1982, by 96 Stat.