He first returned to the practice of law in 1920 after losing the election as vice president along with presidential candidate James M. Cox. He joined the firm of Emmett, Martin, and Roosevelt in New York City.

He also practiced law with Basil O’Connor in New York City from 1924 until 1933. Roosevelt met O’Connor, a Harvard law graduate and promising attorney, in New York City in 1920. O’Connor served as a legal adviser to Roosevelt. The two formed their own law partnership in 1924 and practiced until Roosevelt became president of the United States.