This particular guideline, called also the rule of ten, applies to a competitive auction when one player contemplates to employ a penalty double even though the opponents have not bid a game contract. This particular action is considered by the player under the following outline below.

Note: The origin of this particular rule of ten is unknown. Any additional information regarding its origin would be greatly appreciated. Source is the ABTA website. Note also that this particular rule of ten is not included in any official documentation of the American Contract Bridge League such as The Official Encyclopedia of Bridge.

The criteria to be considered by the player, who wishes to double for penalty, even though a game contract has not been reached, is as follows. The general guideline is to employ the rule of ten only when the partscore is in one of the two Major suits. If the partnership wishes to extend the rule of ten also to the two Minor suits, then this is normally an individual partnership agreement.

1.	The combined values of the partnership exceeds 20 high card points.
2.	There is no suit fit to be found with partner.
3.	Trump winners plus the bidding level of the opponents equals ten plus.

Illustration

	North 10xx Axxx Axx xxx
West AQx Jxx KQxxx Qx		East xx KQxx xx Axxxx
	South KJxxx xx AJx KJx

South		West		North		East		Meaning
1								Promises a 5-card plus Spade suit and opening values.
		2						Promises generally opening values and a 5-card Diamond suit.
				2				Shows a limit raise in Spades.
						Pass		No bid at this time.
Pass		Double						Penalty double according to the rule of ten.

In the above auction all parameters of the rule of ten are met by West:

1.	The combined values of the partnership exceeds 20 high card points.
2.	There is no suit fit to be found with partner. Since the auction has ceased on the two level, then the assumption is that East must have at least 6 plus high card points.

Therefore, since West holds Ace-Queen-x, presumably two winning tricks, in the Major suit of South and the level of the contract at this point is on the two level (which equals 8), then, by partnership agreement, a double by West equals a penalty double. This decision is reached on the definition of the rule of ten, which states that if the number of winning tricks plus the level of the contract equal 10 (or 2 plus 8), then a penalty double is warranted.

As a result the partner of the doubler, East, will pass the penalty double per partnership agreement.

A general outline of the rule of ten, in order to determine whether the parameters of the rule is met, is presented below.

Opponent's Bidding Level		Tricks Required		# of Trump Winners Required
1		6 + 1 = 7		10 - 7 = 3
2		6 + 2 = 8		10 - 8 = 2
3		6 + 3 = 9		10 - 9 = 1

 

If you wish to include this feature, or any other feature, of the game of bridge in your partnership agreement, then please make certain that the concept is understood by both partners. Be aware whether or not the feature is alertable or not and whether an announcement should or must be made. Check with the governing body and/or the bridge district and/or the bridge unit prior to the game to establish the guidelines applied. Please include the particular feature on your convention card in order that your opponents are also aware of this feature during the bidding process, since this information must be made known to them according to the Laws of Duplicate Contract Bridge. We do not always include the procedure regarding Alerts and/or Announcements, since these regulations are changed and revised during time by the governing body. It is our intention only to present the information as concisely and as accurately as possible.