Laws of Cricket 1947 Code - Law 43
The Wicket-keeper shall remain wholly behind the wicket until a ball delivered by the Bowler touches the bat or person of the Striker, or passes the wicket, or until the Striker attempts a run. Should the Wicket-keeper contravene this Law, the Striker shall not be out except under Laws 36, 37, 40 and 41 and then only subject to Law 46.
Note on Law 43
1. This Law is provided to secure to the striker his right to play the ball and to guard his wicket without interference from the wicket-keeper. The striker may not be penalised if in the legitimate defence of his wicket he interferes with the wicket-keeper.
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