The reserve clause, in North American professional sports, was part of a player contract which stated that the rights to players were retained by the team upon the contract's expiration. Players under these contracts were not free to enter into another contract with another team. Once signed to a contract, players could, at the team's whim, be reassigned, traded, sold, or released. The only negotiating leverage of most players was to hold out at contract time and to refuse to play unless their conditions were met. Players were bound to negotiate a new contract to play another year for the same team or to ask to be released or traded. They had no freedom to change teams unless they were given an unconditional release. In the days of the reserve clause, that was the only way a player could be a free agent. Once common in sports, the clause was abolished in baseball in 1975. The reserve clause system has, for the most part, been replaced by free agency. Baseball history In the late 19th century, baseball in America became popular enough that its major teams began to be businesses worth considerable amounts of money, and the players began to be paid sums that were well above the wages earned by common workers. To keep player salary demands in check, team owners promulgated a standardized contract for the players, in which the major variable was salary. The players unsuccessfully tried to fight the growing reserve system by forming a union, the Brotherhood, and founding their own Players' League in 1890, but the PL lasted just one season. For the next 80 years, the reserve system ruled the game. In this era, all player contracts were for one year. There were no long-term contracts as there are today, because the reserve clause negated the need for them. The reserve clause's inception was in 1879, when it was proposed as a way to formalize an unofficial rule known as the "five man rule". It would allow teams to reserve players for each season, unless a player opted out of his contract and did not play in the league for a year. While the previous informal rule was not secret, teams had started to sign other teams' "reserved players", thus encroaching the rule. The resulting controversies caused the National League to instate the rule officially on December 6, 1879. Teams realized that if