What is the LBW rule in cricket?
Leg before wicket dismisses a batter whose body — usually the pad — stops a ball that would otherwise have hit the stumps. Without it, batters could simply stand in front of the wicket and block everything with their legs.
For an LBW to be given, several conditions must all be satisfied.
The ball must not have hit the bat first. Any edge onto the pad rules it out.
Where the ball pitched matters. If it pitches outside leg stump, the batter cannot be out LBW, however plainly it would have hit. This protects against bowling round the batter's legs. Pitching outside off stump is fine.
Where it struck matters. If the impact is in line with the stumps, the batter can be out whether or not they played a shot. If the impact is outside the line of off stump, they can only be out if they made no genuine attempt to play the ball — offering no shot removes that protection.
It must have been going on to hit the stumps. The umpire judges the ball's onward path.
Ball-tracking technology has made the last point contentious. Under the Decision Review System, a portion of the ball must be predicted to hit the stumps for a not-out decision to be overturned. If it is marginal, the on-field umpire's original call stands — this is umpire's call, and it is why identical-looking deliveries can produce different outcomes depending on what the umpire said first.
A batter given out LBW cannot be caught out on the same delivery; the ball is dead once the appeal is upheld.