
The umpire will consider an LBW (which stands for "Leg Before Wicket) decision if he believes the ball would have hit the stumps had its path not been obstructed by the batsman's pads or body. But the umpire also has to take certain factors into consideration before making a decision these inlcude how much spin or there was, was the ball going to bounce over? or was it too wide to hit the stumps?... he also has to consider....

The most important factor when an umpire considers an lbw decision is whether the ball pitched outside leg stump. If the ball lands outside the line the of leg stump, the batsman cannot be given out - even if the ball would have gone on to hit the stumps.

A batsman cannot be given out if either umpire calls a no-ball. The most common way this happens is when the heel of the bowler's front foot lands on or in front of the popping crease (the front line of the batting crease). There are 12 other situations when the umpires can call a no-ball.

A batsman cannot be given out if the ball hits the bat before the pad.

A defence against an lbw appeal for a batsman is to get his pad outside the line of off stump. An umpire will turn down any appeal if he believes the ball has struck the batsman's pad outside the line of the off stump, even if the ball would have gone on to hit the stumps. Unless...

...the batsman makes no genuine attempt to play a stroke. The outside off stump defence becomes redundant.

In this situation, the ball has pitched on the stumps and has struck the batsman on the pads in front of the wicket. The ball has not pitched outside the line of leg stump. And it has not struck the batsman outside the line of off stump. Therefore the umpire should give the batsman out. But a lot of the time it is never this simple... .

Batsmen can create doubt in an umpire's mind by taking a big stride down the pitch with their front foot. By moving further down the pitch, the batsman lengthens the distance between the ball and the stumps. If he is struck on the pad a long way down the pitch, the umpire has a more difficult job to assess whether the ball would have gone on to hit the stumps. But if a batsman is struck while on his back foot or back pad, there is a shorter distance to judge between the batsman and the stumps, strengthening the bowler's appeal for an lbw decision.