Laws of Duplicate Bridge

A revoke, failure to follow suit when a player is able to, is handled by Laws 61-64. A revoke may be corrected (correct card substituted) without trick penalty before any player of the offending side plays to the next trick; otherwise, it becomes established. If a revoke is corrected, the exposed card becomes a penalty card and the opponents may change their played cards as they see fit (however, the revoking side may not take advantage of those seen cards—see Alcatraz coup).

When a revoke is established, in general, if the revoking player won the trick, that trick, plus one of any of the tricks won by the offending side subsequent to the revoke, are transferred. Otherwise, if the offending side won the revoke trick or a subsequent trick, one of those tricks is transferred to the opponents. (If the offending side did not win the revoke trick or any subsequent tricks, no penalty is assessed.) Additional tricks can be transferred if the revoke has caused more damage to the opponents than was redressed by those penalties. A revoke on trick 12 must be corrected, without rectification, if discovered before all four hands are returned to the board.

When a player makes a call when it was not his turn to bid, the laws 30-32 specify various penalties depending on whose turn it was, and whether the call out of turn was a pass, bid, or a double/redouble. Briefly, after a call out of turn, the offender must make a call with the same or similar meaning, or their partner must pass for the remainder of the auction. The partner, rather than the offender, is prevented from bidding because it is the partner whose bid might be affected by unauthorised information.

In addition, the offending side may be subject to restrictions in the opening lead. As a special case, no penalty is assessed when it was right-hand opponent's (RHO) turn to bid and he elects to pass. Finally, an adjusted score can be awarded if the redress was not adequate to the inflicted damage.

After a player makes an insufficient bid (Law 27) (of lesser rank than or equal rank to the last bid at the table), the LHO first receives the option to accept it, in which case no penalty is assessed. An insufficient bid is deemed accepted if LHO has called. If rejected, the offender without penalty may replace the bid with a higher legal call that conveys the same information (but the information remains unauthorized to his partner). If the election is not to do this, or if no suitable call exists, the offender's partner must pass to the end of the auction.

An inadmissible double or redouble is canceled (as is any immediate call by LHO) and must be substituted by a legal call. The offender's partner must pass to the end of auction.

When a card is exposed by one of defenders (law 50), by means of holding it in such a position that it can be plausibly seen by the offender's partner, in general, it becomes a penalty card. If exposed inadvertently, depending on its rank, it may be a minor (2-9) or a major (10-A) penalty card; however, any card may become a major penalty card if played out of turn. In any case, the penalty card must be played at first legal opportunity, which allows the declarer to organize his play to take advantage of the situation. However, the offender may play an honor of the same suit instead of the minor penalty card. There is no penalty whatsoever for the exposition of declarer's cards, provided it was played inadvertently (a card apparently played advertently may not be retracted except for the purpose of revoke correction).

If a card is exposed during the auction (law 24), it may become a penalty card, and offender's partner may be forced to pass to the end of auction.

In general, only the defenders are subject to penalties for opening lead or other play out of rotation (law 53-59). The offender's LHO may accept the lead. If not, the lead reverts to the correct player, and the card led out of turn becomes a major penalty card.

An opening lead out of turn (law 54) is perhaps the most frequent infraction. If the wrong defender makes the opening lead, the to-be-declarer has the following options:

• Accept the lead, spread his hand and become the dummy, and his partner declarer
• Accept the lead, spread partner's hand as dummy and play second from declarer's hand
• Refuse the lead. The illegally led card becomes a major penalty card

Unauthorized information (UI) (law 16) is any information that a player obtains by means of:

• Partner's remarks, questions, mannerisms, hesitation and similar,
• Information from calls and plays which were legally withdrawn and/or substituted as a consequence of that side's infraction (the non-offending side may use this information),
• Overhearing remarks at other tables or seeing a wrong card.

Reception of unauthorized information is not an infraction per se. However, the player who (might have) received it has severe limitation that (s)he may not act on the basis of it (even if the action is reasonable), but must select a logical alternative instead. The definition of logical alternative is fairly strict, and includes all but practically inadmissible alternative actions. However, in the (fairly unlikely) event that the logical alternative becomes a successful one rather than the action suggested by the UI, no further redress is given to the non-offending side.

The exception is when the player receives a UI inadvertently, as by overhearing remarks at other tables. In that case, the director may adjust positions, appoint substitutes, or award an adjusted score.

It may happen that when a player is asked to explain a partnership understanding, the explanation they give is either incorrect, or that their partner gains unauthorized information (that they have bid incorrectly). Law 75 covers the proper procedure to address such a situation.

In the 1932 Laws of Contract Bridge, no trump tricks bid and made, and undoubled no trump tricks made but not bid, score 30, 40, 30, 40, 30, 40, 30.[5]^{: law 30}

In 1935 this became 40, 30, 30, 30, 30, 30, 30.[6]^{: law 39}

Redoubled undertricks have always scored twice as much as the same doubled undertricks.

The 1987 change, to the scoring of the fourth and subsequent non-vulnerable undertricks, was made after a hand in the finals of the 1981 Bermuda Bowl. Munir and Fazli, playing for Pakistan, bid skilfully to reach a vulnerable 7 hearts, which would have scored them 2210. But their non-vulnerable opponent Meckstroth then sacrificed in 7 spades on a weak hand with fives spades to the jack. This went nine off doubled for a score of -1700, a profitable sacrifice. The change of scoring increased the penalty from -1700 to -2300.[9]

Also, the "insult bonus" for making a redoubled contract used to be only 50. This was changed to 100, so that playing 5 of a minor, redoubled, making an overtrick, is always worth more than an undoubled small slam.

It has always been the intention of every official set of Laws of Contract Bridge to forbid contracts for more than seven tricks. Some versions have stated this more clearly than others, but this intention of the Laws has never changed.

When International Match Points were first introduced in Europe, they were as in this table.[10]

On September 1, 1962, they were changed to the table below.[11]^{: law 87}

(after 1972, before 2002) they were changed again (FBDis, p. 22, p. 74)