 He was a member of the Conference of Senior Circuit Judges (now the Judicial Conference of the United States) from 1926 to 1938.His service terminated on February 7, 1939, due to his resignation.In 1922, President Warren G. Harding considered appointing Manton to the Supreme Court of the United States to succeed Justice William R. Day in what was then regarded as the "Catholic seat" on the Court.