Laws of Cricket 1980 Code - Law 27
1. Time of Appeals
The umpires shall not give a batsman out unless appealed to by the other side which shall be done prior to the bowler beginning his run-up or bowling action to deliver the next ball. Under Law 23.1 (g) (The Ball Becomes Dead) the ball is dead on "over" being called; this does not, however, invalidate an appeal made prior to the first ball of the following over provided "time" has not been called. See Law 17.1 (Call of Time).
2. An Appeal "How's That?"
An appeal "How's That?" shall cover all ways of being out.
3. Answering Appeals
The umpire at the bowler's wicket shall answer appeals before the other umpire in all cases except those arising out of Law 35 (Hit Wicket) or Law 39 (Stumped) or Law 38 (Run Out) when this occurs at the striker's wicket.
When either umpire has given a atsman not out, the other umpire shall, within his jurisdiction, answer the appeal or a further appeal, provided it is made in time in accordance with 1 above (Time of Appeals).
4. Consultation by Umpires
An umpire may consult with the other umpire on a point of fact which the latter may have been in a better position to see and shall then give his decision. If, after consultation, there is still doubt remaining the decision shall be in favour of the batsman.
5. Batsman Leaving his Wicket under a Misapprehension
The umpires shall intervene if satisfied that a batsman, not having been given out, has left his wicket under a misapprehension that he has been dismissed.
6. Umpire's Decision
The umpire's decision is final. He may alter his decision, provided that such alteration is made promptly.
7. Withdrawal of an Appeal
In exceptional circumstances the captain of the fielding side may seek permission of the umpire to withdraw an appeal providing the outgoing batsman has not left the playing area. If this is allowed, the umpire shall cancel his decision.
Reproduction of the Laws of Cricket is by kind permission of Marylebone Cricket Club