He was counsel to the National and American League baseball clubs, defeating the application of the Sherman Antitrust Act to their activities in Chicago in 1915 before judge Kenesaw Mountain Landis in preliminary injunction case. However, it was revived four years later after the Black Sox Scandal and his clients received an unfavorable jury verdict, which was reversed by the Supreme Court in Federal Baseball Club v. National League (1922) after lawyer Pepper and Judge Landis (who by then became baseball Commissioner) revised the leagues' organizational structure, Pepper writing the caption for the new series of agreements, "Play Fair. Play Hard. Play for the Team."