 After the railroad, he formed several law practices in New York with various prominent men, including "Emott, Burnett & Hammond" (with former judge James Emott, Henry B. Hammond, and Charles C. Emott in 1875), which litigated for and against the Railways, "Emott, Burnett & Kidder" (with Camillus George Kidder in 1877), "Bristow, Peet, Burnett, & Opdyke" (with Benjamin Bristow, a former Secretary of the Treasury, William Peet, and W. S. Opdyke in 1878), and "Burnett & Whitney" (with Edward Baldwin Whitney in 1883).He was notable involved in representing the English bondholders in the Emma Silver Mine litigation.In 1898, President William McKinley, his close friend, appointed Burnett federal district attorney for the southern district of New York.