FitzHenry was an unsuccessful candidate for election in 1910 to the 62nd United States Congress, but was elected as a Democrat to the 63rd United States Congress, serving from March 4, 1913 to March 3, 1915. He was an unsuccessful candidate for reelection in 1914 to the 64th United States Congress, and thereafter resumed the practice of law in Bloomington from 1915 to 1918. He was an unsuccessful candidate for election as a Justice of the Illinois Supreme Court in 1915.[1]
FitzHenry was nominated by President Franklin D. Roosevelt on June 3, 1933, to a seat on the United States Court of Appeals for the Seventh Circuit vacated by Judge George True Page. He was confirmed by the Senate on June 10, 1933, and received his commission on June 16, 1933. His service terminated on November 18, 1935, due to his death in Normal, Illinois.[2] He was interred in Bloomington Cemetery in Bloomington.[1]