One of Marvin Miller's first victories as head of the Major League Players Association was to negotiate a contract that would pay the players a bit of money by having their own licensing system where the players (and the MLBPA) could make some money off of the player's likenesses.
However, in Japan, that's not the case. And the players were denied in court the right to market their own likenesses on baseball cards and other souvenirs.
At issue was a provision in the 1951 unified contract that all professional ballplayers must sign when joining their respective clubs. The provision states that the right to players' likenesses and copyrights belong to the club and that the athletes will file no objections regarding how those rights are used in advertising.