Career
Born in Mount Olive, Illinois, Poos received an Bachelor of Laws from Saint Louis University School of Law in 1924. He was in private practice in Mount Olive from 1924 to 1939, and then in Hillsboro, Illinois until 1958. Poos was confirmed by the United States Senate on August 19, 1958, and received his commission on August 21, 1958.
He served as chief judge from 1966 to 1972, assuming senior status on August 31, 1973.
Poos served in that capacity until his death, in 1976.