Gambling on baseball refers to the practice of wagering money on the outcome of a future game, or of a championship, with the possibility of gaining a large sum if the predicted outcome occurs, or losing it if it doesn't. It is almost as old as the sport itself and was particularly widespread in the 19th century. The problem with gambling is that those who have money riding on the outcome of a game will sometimes take special measures to ensure the right outcome, which may include making payouts to various persons involved in the contest to ensure that result. This is of course illegal, and if it is known to happen, will have a negative impact on the interest of fans, who will not want to pay good money to watch a game that is not "on the level".
The first major scandal linked to gambling took place in 1877, when four members of the Louisville Grays, including star pitcher Jim Devlin, were accused of taking money in exchange for losing games late in the season. All four received lifetime bans. However, in spite of such decisions from time to time, gamblers continued to wager important sums on the result of professional baseball games, and attempted to influence the outcome of games in various ways in order to minimize their risk. Things came to a head during the 1919 World Series which were tainted by the Black Sox Scandal. This forced baseball to finally act decisively: the owners appointed a sitting federal judge, Kenesaw Mountain Landis, as the first Commissioner and he made it his mission to uproot gambling throughout organized baseball. Eight members of the 1919 Chicago White Sox were banned for life, even though they were found not guilty by a jury in a court of law: Landis felt that their testimony was clear and incriminating enough to justify such radical action. Others linked to gambling also felt the wrath of the commissioner, and he succeeded in cleaning up the game to a large extent.
While there were some minor scandals in the following decades (such as the decision to force Philadelphia Phillies owner William D. Cox to sell the team, or the banning of former stars Mickey Mantle and Willie Mays because they had accepted to work as greeters for a casino), there were no major issues until the Banning of Pete Rose in 1989. That scandal was a major one, and many feel it contributed to the early death of Commissioner Bart Giamatti, who had to take the decision to issue a lifetime ban to one of the game's most popular characters on the basis of partial but very damaging evidence revealed in the Dowd Report. This however served to reaffirm that Major League Baseball remained as forceful as ever on the issue of not allowing gambling to come anywhere close to the game.
There have been numerous gambling scandals in other countries as well. In Japan, the Black Mist Scandal (1969-1971) led to the lifetime suspension of six players. In Taiwan, meanwhile, whole teams have been wiped out by gambling scandals, such as the China Times Eagles and Chinatrust Whales.
All this is taking place in a context where betting on sports events is legal in parts of the United States (most notably the state of Nevada) and many foreign countries, and when the internet has made it simple for persons to place bets abroad from the comfort of their homes. Betting on games or events within a game became even more prevalent following a 2018 decision by the Supreme Court of the United States striking down a ban on sports betting legislated in 1982. Baseball has been pretty much powerless to stop that evolution, but that has not prevented it from continuing to enforce existing rules pertaining to gambling in order to protect players and fans.
- Bob Nightengale: "MLB is powerless to stop gambling on baseball. That doesn't mean it should endorse it.", USA Today Sports, May 14, 2018.