During the evolution of the game of bridge the introduction and employment of the immediate Strong Jump Shift response by the responder, signifying a minimum of 15-16 high card points plus and a 6-card suit, became standard. This action was forcing and many bridge players and bridge authorities considered it forcing to game. However, it soon became evident that the frequency of such a holding held by the responder was very low and restricted the frequency of employing a Jump Shift first response.
Evolution of the Principle
In the evolution of the game of bridge it soon became evident that even a normal response had the same effect of being forcing, since any response by the responder continues to be forcing for one round. Therefore, another interpretation of the immediate Jump Shift response became a necessity and essential.
Instead of being strong, the immediate Jump Shift became weak, just the opposite of its original conception. It informed the partner, generally also the defenders, that the holding was weak in values. The holding could indeed have fewer than the generally required 5/6 points for a normal response. The length of the suit is limited to a minimum of 6 cards, but the suit may contain more than only six cards. The partnership agreement is that the weak jump shift first response is preemptive.
When the bridge player considers the frequency, with which the weak jump shift may be employed, then it becomes obvious and logical that this definition is preferable. The bridge player can also calculate that the employment of a weak jump shift can be employed twelve times only. When the partner bids 1 Club, then the responder has only three possibilities to make a weak jump shift, which is also true by an opening of 1 Diamond, and 1 Heart, and 1 Spade.
With one response via the employment of a weak jump shift, the responder can adequately describe the holding and the minimum range of held values, namely zero points to about 5 high card points. However, many bridge players have not favored the weak jump shift when the responder holds zero to a Queen, or two high card points. This becomes a matter of partnership agreement.
This jump shift by the responder also denies any support for the suit of partner.
The examples below should clarify this concept of the weak jump shift by responder. The bridge player should be aware of the fact that the weak jump shift is preemptive in nature. If the opponents wish to enter the auction, then the opponents must do so on or above the level of the preemptive weak jump shift.
It is also the obligation and decision of the responder whether to compete if the immediate opponent, following the opening bid, also competes by bidding a suit. This bidding sequence creates a different situation, to which the responder must adapt and decide whether it would be more favorable to compete or to pass, awaiting any further and possible action by partner.
Example 1:
| North |
|
East |
|
South |
|
Meaning |
1  |
|
Pass |
|
3  |
|
The 3 Hearts first response shows weak values and a desire to play in Hearts. Those partnerships valuating with the losing trick count method will notice that the holding of the responder contains 7 losing tricks. Compare with Example 2. |
In the above example, South has very few values, insufficient to make even a 1 No Trump response. In the fortunate situation that East passes, South has the opportunity to employ a weak jump shift of 3 Hearts. Although East and West may have the majority of the high card points, it will prove difficult for East and West to compete at the four level and perhaps find their fit in Clubs.
Example 2:
| North |
|
East |
|
South |
|
Meaning |
1  |
|
Pass |
|
2 |
|
The 2 Hearts first response shows weak values and a desire to play in Hearts. Those partnerships valuating with the losing trick count method will notice that the holding of the responder contains 9 losing tricks. Caution is advised with Example 2 in relationship to Example 1. |
In the second example, South again has very few values, insufficient to make even a 1 No Trump response. In the fortunate situation that East passes, South has the opportunity to employ a weak jump shift of 2 Hearts. East and West, if they wish to enter the auction, are forced to enter the bidding process on the two level or higher.
Note the following auction and compare the possibility of employing the weak jump shift:
By this bidding sequence, whereby the immediate opponent enters the auction with 1 Diamond, then the effectiveness of the weak jump shift still retains its preemptive nature. The overcall has interfered with the conventional method and the partnership therefore plays systems on. Compare with the following auction:
| North |
|
East |
|
South |
| 1 |
|
1 |
|
? |
By this bidding sequence the immediate opponent, East, has removed the possibility of employing a weak jump shift. If South still wishes to employ the weak jump shift, then South must preempt on the three level. Depending on the vulnerability and other factors this may not be the most preferred action. South must make the decision as to whether to bid on the three level or to pass, awaiting any possible action by partner.
Example 3:
| North |
|
East |
|
South |
|
Meaning |
| 1 |
|
Pass |
|
2 |
|
The 2 Spades first response shows weak values and a desire to play in Spades. Those partnerships valuating with the losing trick count method will notice that the holding of the responder contains 9 losing tricks. Caution is advised with Example 3 in relationship to Example 1. |
In the third example, the situation is the same. South again has very few values, insufficient to make even a 1 No Trump response. In the fortunate situation that East passes, South has the opportunity to employ a weak jump shift of 2 Spades. East and West, if they wish to enter the auction, are forced to enter the bidding process on the three level.
Additional Principles of the Concept
The concept behind the weak jump shift is to inform the partner immediately of the fact that there is no support for the suit bid or intended to bid, except the suit preempted by the responder, and that the values are not present for a normal response. The values for a weak jump shift are normally less than the values required for a Weak Two opening, generally a King-Jack or less.
The auction does not necessarily cease once the responder has made a weak jump shift in his suit. The opener may have more values and will continue to bid, requesting further and additional descriptive information from the responder.
Some authored publications maintain that any rebid by the opener is forcing for one round. This basic principle was incorporated into the conventional method as soon as it was devised. However, this principle has proven to be not exactly correct based on the gathered information at the various tournaments.
The rebids by the opener following a descriptive preemptive bid by partner, if any, are conditional continuations, which should be decided by the partnership. The only truly rebid for a one-round forcing rebid by the opener is a rebid of 2 No Trump if the bidding sequence allows this rebid on the two level. However, the rebid of 4 No Trump may be only understood as an Ace or Keycard inquiry, and is definitely forcing.
The general approach is explained below:
Rebids by the opener:
| 1. |
2 No Trump is forcing and shows a 2-card support for the suit of the responder. The responder must bid three of his suit with minimum values. |
| 2. |
A rebid on the three level by the opener of the suit preempted by his partner is also considered preemptive, which serves to continue to hinder the opponents from finding a fit. |
| 3. |
Any new suit or rebid of the suit of the first bid suit by the opener is considered natural and non-forcing. |
| 4. |
Any jump bid by the opener is considered to be natural and invitational, and in certain bidding sequences asking suit preference. |
| 5. |
Any rebid on the four level by the opener of the suit preempt by his partner is invitational and considered competitive, mainly in tournaments, especially after an immediate overcall. |
| 6. |
Any game bid is to play and is a sign-off. |
| 7. |
The rebid by opener of 4 No Trump is regarded as an Ace or Keycard inquiry, and should be deemed forcing. |
| 8. |
A pass by the opener is completely acceptable if the opener cannot indicate any additional values. However, see # 2 for preemptive rebids. |
Note that this list of possible and additional continuations has accumulated over time since the original version was introduced. Additional features can be included and, as such, are to be considered as an individual agreement between both partners.
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.