jammer 2

Partner leans over the table and whispers, “Psst, pard, I found a terrific new gadget for our two diamond spot. It’s called Jammer, because it ‘jams’ the auction. Flannery is useful, but I never seem to have the hand for it. Jammer comes in different versions, and the one I like happens almost FOURTEEN times as often as Flannery. That means you will open two diamonds in first seat as often as you open one spade or one club. Jammer is a suitless pre-empt, about as safe as a three-level opening with seven cards, and way less risky than those dumb six-card pre-empts you sometimes make. So it happens a whole lot, it carries acceptable risk, we will find defensive fits we could not otherwise, and it will really annoy the opponents. Interested?” I had to agree I was.

 Before I describe this bid, let me introduce the concept of the ‘lawfulness’ of a bid, which will show that Jammer is a relatively ‘safe’ bid, as well as facilitate a comparison of Jammer with other shape-showing bids. Consider a bid which serves primarily to identify the length of a suit or suits … for example a Michaels cuebid. How often can we expect the best fit with intervenor’s suits to comply with the Law?  For a two heart bid showing spades and, say, clubs, some two spade contracts will have a combined seven trumps (advancer holds pattern 2=5=3=3 say) and some three club contracts will have ten trumps (advancer holds 2=2=4=5 say). Given a suitably large sample, what are the chances of the various holdings that might arise?

 According to the Law, it makes bridge sense to compete to the two level with eight trumps, and to the three level with nine trumps. In what follows I have ignored any implications due to skew, the notion that eight-zero fits might or might not be preferable to four-four fits.  Now consider the symbolism ‘(A, B, C, D)’, where A is the percentage of times you will have two fewer trumps than the Law number (or worse), B is one fewer, C is the Law holding, D is more than the Law requires. In English, the summary approximately would be (% very poor fit, substandard, good, great). The calculation for some bids is trivial and available from published distribution tables  … for a pre-empt with a seven card suit at the three level, 3 ~ (7, 26, 36, 31), simply reflecting the chances of the opening bid facing a void, singleton, doubleton, three or better. To investigate more complicated positions, you will need a hand generator and a suitably large sampling of deals. For a Michaels two heart bid showing spades and say clubs, 2 ~ (3, 19, 38, 40).  Here the ‘good’ C element means in 38% of deals, the partnership will have either eight trumps for a two spade contract, or nine trumps for three clubs. The ‘poor’ A factor represents those misfits when intervenor has perhaps 5=2=1=5 pattern, and his thoughtless partner holds something like 1=5=5=2. Compared to other shape-showing bids, Michaels two hearts is very lawful ... those are low A and B elements … compare with the traditional three club opening above. 

Jammer Two Diamonds is a weak three-suiter, liberally defined to include three-card suits, so to include patterns 4-4-3-2 (22% of all hands), 5-4-3-1 (13%), 4-4-4-1 (3%) and 5-4-4-0 (1%), comprising in total some 39% of all hands. Consider it a modest pre-empt in one of three suits, with the suit not yet established, but with foreknowledge there is a good chance of a lawful fit. It is possible to play Jammer wide open as described, with nothing more known about the distribution of the hand. However at the end of the day, only half your fits will be lawful, since unfettered 2 ~ (14, 35, 30, 21), and the high A component will be too frisky for most partnerships (although still more lawful than six-card preempts at the three level!). If you did choose to play this, with a range of 4-9 HCP about 15% of your hands would qualify, and you would open two diamonds more often than any bid except pass. The pre-empt is safer if we know more about the hand, although opportunities to bid are fewer. I will describe two variations, one where opener guarantees at least four spades, another where the short suit is always clubs.

The variant I prefer is long spade Jammer … same shapes, but opener guarantees at least four spades. At 2 ~ (7, 31, 34, 28), the B component is a little higher than you might like, but manageable. With a 4-9 HCP range, nearly 7% of your hands will qualify, so it will arise about as often as any bid you make. It is a little less lawful than a pre-empt with a seven card suit, but still, nearly two-thirds of your trump fits will be good or better. And it is not as if a B contract is the end of the world … most of that component reflects 4-3 fits at the two-level. The opponents have no way of knowing your fit is not good because you will not stagger into your contract, you just bid it with a big smile. 

When responding to Jammer, remember these facts. Opener is a 90% favorite to have a three-card suit. He will have four spades about 80% of the time, and five about 20%. Opener’s shortness will be two cards a little more than half the time, and a singleton most of the rest. If you have a two-suited hand, neither one spades, you are guaranteed a fit in one suit but remember it might be opposite opener’s three-suiter. You often have a fallback in the known spade suit. Even if you hold some balanced 4-4-3-2 shape, without four spades, you will have a poor fit just 6% of the time. Your most awkward responding hands are short one-suited like 2=5-3-3 with short spades, where often your length is opposite opener’s shortness, so you must be prudent with these.

 I will describe briefly the response principles I used to develop 2 ~ (7, 31, 34, 28). No system can produce a double dummy result, where you always land in the optimum contract. A double-dummy summary would be 2 ~ (0, 22, 44, 34), and the closer we can come to that, the better. Consider 2=3=3=5 in responder, an awkward holding for Jammer. The ‘book’ response is two hearts and not three clubs, tested over thousands of deals. However, when opener holds 4=3=1=5 you happen to land in a very poor 3-3 fit, missing the somewhat better 5-5. Oops, not good, but don’t lose sight of the fact that any shape-showing bid produces disastrous results from time to time; don’t you just love partner’s unusual notrumps when you hold 5=5=2=1?

 Opener will pass a response of two hearts, unless that is his shortness, in which case he will rebid two spades. He will pass two spades. He passes three clubs. The only forcing non-jump responses are two notrump, which asks for opener’s best minor but might be the start of an invitational sequence, and three diamonds (responder can pass two diamonds if weak with diamonds), which says bid your cheapest suit. The general rule for responder is simply this: bid the cheapest of two suits (and three spades constitutes a ‘suit’ in most cases), and be prudent with balanced hands. If you have four or more spades, bid spades unless you have five or more hearts, when you first should try two hearts. If you have a long club suit, bid three clubs and opener must pass. With long diamonds, pass. With both minors, bid two notrump. For strong or shapely hands, three hearts or spades are pre-emptive, but invitational if rebid after a two notrump query …. 2/2N//3/3 is invitational in spades. Three diamonds is forcing and says bid your suits up the line, skipping spades.

For responder, the spade suit is a safe harbour. For example, holding 3=2=4=4 or 3=1=5=4 he might be tempted to try for opener’s best minor with two notrump, hoping for something like 4=1=5=3 in opener … but he should not because it does not pay off long term. Partner is marked with hearts, and too often will hold something like 4=5=1=3 or 4=4=2=3 (intervenor did not bid hearts), so responder should take his Moysian lumps in a two spade contract … 20% of the time partner will surprise with five of them. When in doubt, bid conservatively; the opponents will have no idea what kind of fit you have. 

Here are some examples of auctions where responder holds minimum hands, where the lawfulness of this small sampling is ~ (10, 30, 30, 30). 

Opener has

Responder has






4-3 cat B




4-4 cat C




3-5 cat B




5-4 cat D




4-4 cat C




3-6 cat D




2-7 cat B




4-5 cat C




4-5 cat D




3-4 cat A

 Another interesting variant is Short Club Jammer, where the shortness is restricted to the club suit. This is a very lawful bid, and easy to use. The price you pay for increased lawfulness is reduced frequency. If you play a range of 4-9 HCP, some 4% of your hands will qualify, compared to 7% for the long spade version. Still, this is approximately four times as often as you would hold a weak two diamond bid, and about four times you make a seven-card pre-empt.

For short club Jammer, 2 ~ (6, 22, 41, 31), more lawful than a seven-card three-bid. Responses for weak hands are these: bid a long major, pass with 5+ diamonds, bid two hearts with four hearts, bid two spades with four spades, pass with four diamonds. What remains are club one-suiters. With six or more clubs, bid three clubs … half the time partner will co-operate with two. With 2-3-3=5 clubs, pass with three diamonds or bid two hearts or spades … you will from time to time land in a 3-3 fit. For stronger responding hands there are many sensible bidding frameworks, maybe three diamonds invitational both majors, three hearts/spades invitational, and two notrump as a forcing relay to three clubs, then three diamonds forcing both majors, three hearts/spades forcing.

 How does the lawfulness of these openings compare to other shape-showing bids? Here are a few, listed in decreasing lawfulness of the bid. The ‘frequency’ guesstimate is necessarily crude, because style will be a large factor The frequency for the non-openers assumes the appropriate opening has already been made ... that is, for two heart Michaels, given that opener has opened one spade, intervenor will have the ingredients for a Michaels bid maybe 3% of the time.


Law Summary



(2, 20, 44, 34)

0.5 %

2 Michaels (5/5)

(3, 19, 38, 40)


6-card Weak 2

(4, 19, 33, 44)


Landy (5/4+)

(5, 20, 36, 39)


Short-Club Jammer 2

(6, 22, 41, 31)


Ekren 2 (9+ majors) (8, 18, 37, 37) 2%

Any 7-card 3-Bid

(7, 26, 36, 31)


Long-Spade Jammer 2 (7, 31, 34, 28) 7%
2 Michaels (5/5) (10, 31, 36, 23) 3%
5-card Weak 2 (16, 29, 31, 24) ? 3%
Wide-Open Jammer 2 (14, 35, 30, 21) 15%
2N Opener Minors (5/5) (17, 35, 32, 16) 2%
Any 6-card 3-Bid (24, 33, 28, 15) ? 4%









There will be the usual vulnerability and positional considerations for pre-emptive bids. You might not want to play Jammer when vulnerable against not, or you might raise the HCP range to 8 to 11, say. Like any pre-empt, it will be most effective in first seat, when the opponents will be in game range half the time. In subsequent seats you might raise the HCP bar somewhat, or play another gadget for which you will never have the right hand.

Smart defences will evolve, but for the beginnings of a Jammer defence, the opponents might try this: with balanced hands, double with 12-14 or 18+, and bid two notrump with 15-17. Suit bids are natural, but beware of possible length in opener. Pass then double would be takeout. Against long-spade Jammer, two spades would be a takeout double of spades.

Jammer is as lawful as many bids you already use. It effectively jams the auction. It arises a lot. It should be an excellent addition to your bidding toolkit.