Bidding in depth
A new-suit bid one level higher than necessary, strong when made freely and weak after an opponent’s double.
A jump shift is a response in a new suit one level higher than necessary: partner opens 1♦, and you bid 2♠ instead of 1♠. BidMaestro gives it the traditional strong meaning: about 19 or more points counting length, and a good five-card or longer suit (two of the ace, king, and queen). It forces the partnership to game and tells partner immediately that slam is possible. With the points but a ragged suit, respond normally; your strength can be shown next round.
| Partner | You |
|---|---|
| 1♦ | 2♠ |
One level higher than the 1♠ that would have done.
Playing 2/1 Game Force, BidMaestro makes the strong jump shift only in a suit whose ordinary response would have been a one-level bid. A one-level response is not a game force, so the jump shows the suit and the slam values together while the auction is still low. Where the ordinary response would already be a 2/1, and so an unconditional force to game, the jump would only spend a level that may be needed to explore slam. Over 1♣ the jump shift applies in any suit; over 1♦ in hearts or spades; over 1♥ in spades only; and over 1♠ not at all, since every response is already at the two level. With 2/1 Game Force switched off there is no 2/1 force, and the jump shift applies over every opening.
If an opponent doubles first, a jump shift indicates weakness, such as a long suit and a poor hand, intending to crowd the opponents. Every source we follow agrees on that.
Our published sources disagree about the details of jump-shifts, including how many points and over which openings, so we settled it by simulation, as described under Research Methodology: the arrangement described above scored best of every alternative we tested.
Opener has a jump shift too. After a one-level response, a jump in a new suit (1♦ – 1♠ – 3♥) is forcing to game. It shows about 19 or more points, an unbalanced hand and a strong second suit of four cards or more. It is one step up from a reverse: with 17–18 opener reverses, forcing for one round; with 19 or more the jump forces to game. With a strong balanced hand opener does not jump in a suit at all: a 2NT or 3NT rebid shows the balanced 18–19.
Made freely, a jump shift shows about 19 or more points counting length and a good five-card or longer suit, and it forces the partnership to game. Playing 2/1 Game Force it applies only in a suit whose ordinary response would have been a one-level bid: any suit over 1♣, hearts or spades over 1♦, spades over 1♥, and never over 1♠. With 2/1 Game Force switched off it applies over every opening. After an opponent’s double it is weak, bid to crowd the auction.
