Only two fielders behind square on the leg-side
The 1932/33 Ashes series, which was played in Australia, was famous for Douglas Jardine-led England’s controversial bodyline bowling tactics, which played an important role for them to win that series by the 4-1 margin.
In these bowling tactics, the bowlers targeted the batsmen’s bodies, including the short-pitched deliveries, as when the batsmen tried to defend the ball, it could create caught out chances. However, these tactics injured several Aussie batsmen, but they escaped from serious injuries.
Many had disliked these bowling tactics, including some English cricketers of that tour. They believed that it was not a rule that supports the fair game.
Though the International Cricket Council (ICC) allows the limited short-pitched deliveries every over, they don’t support the bodyline bowling tactics. At first, the MCC passed a law to remark these bowling tactics as unfair. During that period, the umpires had the duty to identify those bowling tactics and immediately order to stop those.
Later, the rules have allowed only two fielders behind square on the leg-side, and the bodyline bowling tactics are now almost impossible due to this rule.