 Duell moved to Cortland in 1847, and was district attorney of Cortland County from 1850 to 1855.He was Judge of Cortland County from 1855 to 1859.Duell was elected as a Republican to the 36th and 37th United States Congresses, holding office from March 4, 1859, to March 3, 1863; during the 37th Congress, he was Chairman of the Committee on Revolutionary Claims.