Associated Press v. United States
In Associated Press v. United States, 326 U.S. 1, 65 S.Ct. 1416, 89 L.Ed. 2013 (1945), the Supreme Court held invalid an AP by-law which permitted members to impose significant, often prohibitive, penalties on potential competitors seeking to join the organization.
The Court stated:
Trade restraints of this character, aimed at the destruction of competition, tend to block the initiative which brings newcomers into a field of business and to frustrate the free enterprise system which it was the purpose of the Sherman Act to protect. (326 U.S. at 13-14, 65 S.Ct. at 1421.)