This Law was modified, effective from 2024. You can find the previous version here.

COMMUNICATION, TEMPO AND DECEPTION

Proper Forms of Communication between Partners

Communication between partners during the auction and play shall be effected only by means of calls and plays, except as specifically authorized by these laws.
Calls and plays shall be made without emphasis, mannerism or inflection, and without intentional haste or hesitation (but see Law 73D3).

Players must not communicate, nor attempt to communicate, via means other than those described in Law 73A.

When a player has available to him incidental unauthorized information from his partner, such as from a remark, question, explanation, gesture, mannerism, inflection, haste or hesitation, or an unexpected alert or failure to alert, he must carefully avoid taking advantage of it [see Law 16B1(a)].
A penalty may be assessed against a player who violates C1, but if the opponents have been damaged, see also Law 16B3.

It is desirable for players to maintain steady tempo and unvarying manner. Players should be particularly careful when variations may work to the benefit of their side. Otherwise, unintentionally to vary the tempo or manner in which a call or play is made is not an infraction. Inferences from such variations are authorized only to the opponents, who may act upon the information at their own risk.
A player may not attempt to mislead an opponent by means of a question, remark or gesture; by the haste or hesitancy of a call or play (for example hesitating before playing a singleton); by the manner in which a call or play is made; or by any purposeful deviation from correct procedure (see also Law 73E2).
Regulating Authorities may require mandatory pauses, such as on the first round of the auction, or after a skip-bid warning, or on the first trick.

A player may appropriately attempt to deceive an opponent through a call or play (so long as the deception is not emphasized by mannerism, unwonted haste or hesitancy, nor protected by concealed partnership understanding or experience).
If the Director determines that an innocent player has drawn a false inference from a question, remark, manner, tempo or the like, of an opponent who has no demonstrable bridge reason for the action, and who could have been aware, at the time of the action, that it could work to his benefit, the Director shall award an adjusted score.