National Association of Professional Baseball Leagues (NAPBL). MLB could dictate not only how and where professional players could move between major league clubs, but as they took the opportunity of the Great Depression to establish systems of farm teams of players wholly owned by the parent clubs placed on independent teams from the NA leagues around the country, they developed a way of expanding control of contracts of virtually the entire pool of professional baseball players. When other team sports, particularly ice hockey, football, and basketball developed professional leagues, their owners essentially emulated baseball's reserve clause. This system stood largely unchallenged other than by the occasional holdout for many years. In October 1969, St. Louis Cardinals outfielder Curt Flood unsuccessfully challenged his trade to the Philadelphia Phillies and sacrificed the remainder of his playing career to pursue this litigation. In Flood v. Kuhn the Supreme Court established that the reserve clause was a legitimate basis for negotiation in collective bargaining between players and owners, and that the historic baseball antitrust exemption was valid for baseball only and not applicable to any other sport. Although the Court ruled in baseball's favor 5–3, it admitted the original grounds for the antitrust exemption were tenuous at best, that baseball was indeed interstate commerce for purposes of the act and the exemption was an "anomaly" it had explicitly refused to extend to other professional sports or entertainment. Removing the reserve clause from player contracts became the primary goal of negotiations between the Major League Baseball Players Association and the owners. The reserve clause was struck down in 1975 when arbitrator Peter Seitz ruled that since pitchers Andy Messersmith and Dave McNally had played for one season without a contract, they could become free agents. This decision essentially dismantled the reserve clause and opened the door to widespread free agency within North American professional baseball. NFL On June 18, 1921, the NFL ratified its first constitution. The reserve clause ratified in the constitution was similar to that of baseball's at the time. The reserve clause stipulated that a team had the first opportunity to sign a player after the length of the contract had expired. If the team chose not to offer a contract, then the player could try to sign with a team of his choosing. Theoretically, the reserve clause bound the player "...to his employer in perpetuity". The reserve clause had been abolished