‘Bodyline’ was a controversial cricket tactic used by England against Australia in 1932-3 that involved deliberately aiming the ball at the batter’s body. It indirectly led to several changes in the rules of cricket.
The tactic, described by English players as “fast leg theory bowling”, involved fast deliveries designed to bounce and target the player’s body rather than the stumps. The idea was to force the batter to use the bat primarily to block the ball from hitting them rather than to intentionally hit the ball to a position that made it easier to score a run. This blocking created a strong likelihood of the ball flying off into a position where a nearby leg-side fielder could catch it.
Although the tactic was legal at the time, it proved highly controversial and led to ill will and even a diplomatic incident. Australian players and supporters argued that intentionally intimidating the batter with the threat of injury was unsportsmanlike.
While the controversy did not lead to immediate significant rule changes, several changes since have reduced the usefulness of the tactic and thus discouraged it. The most significant is a rule that only two fielders can be behind square (ie behind the batter) on the leg side (eg to the right of a right-handed batter from the bowler’s perspective). This reduces the chance of a catch from a “bodyline” delivery.
Another change is a limit on bouncers (balls that arrive above the shoulder but below the top of the head). This works on a competition-by-competition basis and is usually a limit of one or two such deliveries. This doesn’t strictly affect bodyline bowling, which targeted the body, but does affect the wider tactic of trying to intimidate the batter and force them to make a mistake.