Jean-Marc Bosman was a player in the 2nd division of the Belgian football league, whose contract had expired. He wanted to change teams and move to Dunkerque, a French team. However, Dunkerque didn't offer his Belgian club RFC Liège enough of a transfer fee, so Liège refused to let him go.
In the meantime, Bosman's wages were reduced as he was no longer a first team player anymore. He took his case to the European Court of Justice in Luxembourg and sued for restraint of trade. After a tough legal battle he won his case, and on December 15, 1995 the court gave him and all other EU football players the right to a free transfer at the end of their contracts, with the provision that they were transferring from one EU Federation to another. This case is now widely referred to as the Bosman ruling.