 About 1862, he took Judge Selden's place in the firm of Selden, Munger & Thompson, at Rochester; in 1865 the firm became Church, Munger & Cooke, and so continued until Church's elevation to the bench of the New York Court of Appeals.Church was a member from Orleans County of the New York State Assembly in 1842.Three years later he was appointed District Attorney of Orleans County, and after the New York State Constitution of 1846 became effective, was elected by the people to the same office, serving until the end of 1850.