Douglas quit the Cravath firm after four months. After one year, he moved back to Yakima, but soon regretted the move and never practiced law in the state. After a time of unemployment and another months-long stint at Cravath, he started teaching at Columbia Law School. Douglas later joined the faculty of Yale Law School. There he became an expert on commercial litigation and bankruptcy law, and was identified with the legal realist movement. This pushed for an understanding of law based less on formalistic legal doctrines and more on the real-world effects of the law. While teaching at Yale, he and fellow professor Thurman Arnold were riding the New Haven Railroad and were inspired to set the sign Passengers will please refrain ... to Antonín Dvořák's "Humoresque #7." Robert Maynard Hutchins described Douglas as "the most outstanding law professor in the nation". When Hutchins became president of the University of Chicago, Douglas accepted an offer to move there, which he backed out of once he was made a Sterling Professor at Yale. In 1934, Douglas left Yale to join the U.S. Securities and Exchange Commission (SEC) in a political appointee position, having been nominated by President Franklin D. Roosevelt. By 1937, he had become an adviser and friend to the President and the SEC chairman. During this time, Douglas became friends with a group of young New Dealers, including Tommy "The Cork" Corcoran and Abe Fortas. He was also close, socially and in thinking, with the Progressives of the era, such as Philip and Robert La Follette, Jr., and later with President Kennedy. This social/political group befriended Lyndon Baines Johnson, a freshman Congressman from the 10th District of Texas. In his book "", Robert Caro writes that in 1937, Douglas helped persuade President Roosevelt to authorize the Marshall Ford Dam, a controversial project whose approval enabled Johnson to consolidate his power as a congressman. In 1939, Justice Louis D. Brandeis retired from the Court, and Roosevelt nominated Douglas as his replacement on March 20. Douglas was Brandeis's personal choice for a successor. Douglas later revealed that his appointment had been a great surprise to him—Roosevelt had summoned him to an "important meeting", and Douglas feared that he was to be named as the chairman of the Federal Communications Commission. He was confirmed by the United States Senate on April 4 by a vote of 62 to 4. The four negative votes were all cast by Republicans: Lynn J. Frazier, Henry Cabot Lodge Jr., Gerald P. Nye, and Clyde M. Reed. Douglas was sworn into office on April 17, 1939.