Burnett again moved to New York, this time in Buffalo, where he served as counsel to the Buffalo and Erie Railroad (where his father-in-law was treasurer), until 1874. 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.