The origin of this rule is unknown, but it has been attributed to Mr. Ray Depue. The source of this information is no longer available online. Any additional information would be grealy appreciated. Note: it is necessary to include the fact that the rule of nine, as described below, has not found any inclusion in any of the official publications by the ACBL such as The Official Encyclopedia of Bridge.

Note: Any information as to the person of Mr. Ray Depue would be greatly appreciated. Please include any reference material.

Side Note: In the card game of Blackjack most betting players apply the rule of nine to achieve an above average success rate. This particular rule of nine states that it is a good idea to double down on a hand total of 10 or 11 points. Source.

In certain auctions the opening bidder must determine whether to continue to compete after a low-level overcall has been made, which is then followed by two passes. The rule of nine allows the opening bidder to judge better the possibility of continuing to compete or whether to defend.The rule of nine is a concept employed by the responder after a certain bidding situation, which is described below. An example should clarify the situational element.

North East South West
1 2 Pass Pass
?

The question for North, the opener, is whether to reopen the bidding with a double. The situation is that North has opened the auction, the left hand opponent, East, has made an overcall, which is then followed by two passes. There could be two reasons why South passed:

1. South has insufficient values to compete.
2. South has values and wanted to make a penalty double, but could not since a double would have been interpreted as having a specific partnership agreement.

In determining the correct reason as to why South passed, the inference made by North is that South has values if North is short in the suit of the opponent, two or less. In the case that North holds three or more cards in the suit of the opponent, then the inference is that South has no values, with which to bid.

Therefore, North should follow the guidelines below when deciding to reopen the auction with a double:

1. Reopen the bidding with a double if the number of cards held in the suit of the opponent is two or less. This guideline holds true even if the holding of North is not up to standard for a takeout double or a reopening double.
2. Pass, completing the auction, in order to defend based on the inference that holding three cards or more in the suit of the opponent, partner has no values. This is the normal guideline. In the case that North has substantially more values to continue the auction independently, then North should take such action by bidding another unbid suit or employing a cuebid per partnership agreement and allowing partner to make a preference bid. A double, in this instance, should not be employed.

When North decides to reopen the auction with a double, then the partner should take some action. The rule of nine assists South in deciding to take the correct action. However, the partner, after a reopening double, should:

1. Bid his/her best suit.
2. Raise the suit of the partner, in this case North, with a minimum of two or more but no fewer.
3. Pass for penalty when holding length and defensive values in the suit of the opponent.

The rule of nine can assist the partner, who has been forced to respond, in arriving at the best action. The concept is explained below:

1. The partner, in this case South, adds:
  a. the level of the contract plus
  b. the number of cards held in the suit of the opponent, and
  c. the number of honors held in the suit of the opponent, which includes the ten.
2. If the calculated number is nine or more, then the partner, South, passes for penalty.
3. If the calculated number is eight or fewer, then the partner, South, should bid.

For example, if South, in the above example, held AQ987, which is the suit of the opponent, then the calculation is as follows. The auction is repeated for the convenience of the reader:

North

East South West Meaning
1 2 Pass Pass  
Double Pass Pass The level of the contract equals: 2
  a. If he number of cards held in the suit of the opponent equals: 5
  b. If the number of honors held in the suit of the opponent equals: 2
  The total equals: 9
Since the total equals nine, then according to the rule of nine, South should pass for penalty.
 

North

East South West Meaning
1 2 Pass Pass  
Double Pass Compete The level of the contract equals: 2
  a. If he number of cards held in the suit of the opponent equals: 4
  b. If the number of honors held in the suit of the opponent equals: 2
  The total equals: 8
Since the total equals eight, then according to the rule of nine, South should compete.

 

 

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.

 


     
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