Martin was educated at the Mohegan Lake School in Peekskill, New York. He then studied the law at Yale University and graduated with the LLB degree in 1897. He entered the legal profession and served for five and a half years in Kings County as an assistant District attorney with John F. Clark. When that political appointment ended, he then became a partner in the law firm of Martin and Kesselman, which was situated at 215 Montague Street, Brooklyn. Here he developed a high-profile reputation throughout Kings County as a criminal trial lawyer.