The D.S.I. Double — An Introduction

Playing in the a recent Thursday evening game, my partner, playing West, picked up the following hand:


Neither side was vulnerable. Following her right hand opponent’s pass, my partner passed, as did her RHO.  I opened in 4th seat 1♦.  Partner’s right-hand opponent overcalled 1♠, my partner made the obvious negative double, and her left-hand opponent raised to 2♠.  Two passes later the bidding came back to my partner.

The bidding is given below:


What would be my partner’s best bid and why?  Your choices are:

A.   Pass          B.    Double       C.  3♣
D.   3♦              E.    3♥

Click on the link below to see the answer.

My partner, quite reasonably, passed and so we ended up defending 2 spades by South.  Here are all four hands.


On defense, partner cashed 3 hearts, me encouraging with the ♥2 on the first heart and pitching the ♦3 (encouraging a diamond shift in our methods) on the 3rd heart.  Partner shifted to the ♦2 (showing 3 diamonds).  Seeing the established ♥10 in dummy, I cashed both diamonds and then underled my ♣A.  Declarer misguessed, playing the ♣J so we got 3 hearts, 2 diamonds and 2 clubs for down 2 …. and a terrible board!

Why?  Because despite this excellent defense, most other pairs were in 3 diamonds, making 3 for +110, while we set two spades 2 tricks for 50 a trick, or +100.  As happens in matchpoints, that 10 point difference gave us a bottom.

How do we avoid this horrendous result?  Looking at all four hands, it is easy to see that a bid of 3 diamonds by West does the trick nicely.  So the best bid is 3 diamonds, right?

Not so fast!  That works nicely on these particular cards, but would not be the best bid generally.  Unless I kicked her under the table, there would be no reason for my partner to believe that I necessarily have 5 diamonds — while it is almost certain that I have 4 (given the fact that I did not bid hearts), there is no certainty that I have 5.  What if the hands were as follows:


How would my partner feel about sticking me in 3 diamonds then?

Any other ideas?

The best bid by far my partner could make is the informally-named Do Something Intelligent (D.S.I.) double.  In this particular case, the D.S.I double is a double made in the pass-out seat (typically Responder) after the other side has interfered.  It is primarily a take-out double, but partner may choose to leave it in if that would be the more intelligent choice, something he is more likely the higher the level of bidding.

The requirements for a Do Something Intelligent double made by Responder are the following:

  1.  Shortness in opponent’s suit (a doubleton is okay)
  2.  10+ high card points with length in the unbid suits;
  3.  No clear alternative action.

The idea is that our side opened the bidding and so with responder having 10+ HCP we should have a comfortable majority of the high card points.   Either we should be able to make something at the 3-level or we should be able to set the opponents.

My partner had a perfect hand for such a bid.  She had 11 high card points in the two unbid suits.  She has a doubleton in opponent’s suit; 3 cards in my diamond suit; and 4 cards in clubs.  She thus has no clear course of action, because she can not be sure whether the hand plays better in clubs or diamonds (I should not have more than 2 hearts since I did not make a support double over the 1 spade overcall, but with a weak opener I might have passed even if I had 3 hearts).

A double caters to all possibilities.  If I have 4 clubs and 4 diamonds, I will bid 3 clubs, comfortable that my partner does NOT have 4 diamonds (with 4 diamonds she would have a clear course of action — bidding 3 diamonds — since she knows I have at least 4 diamonds, and hence she would not have made the D.S.I. double).  If I have 5 diamonds, I can bid 3 diamonds in confort that she has 3 diamonds, and so we have an eight-card fit.

But the true beauty of the D.S.I. double is that I have a 3rd choice.  I can pass for penalties!  Having 3 of the opponent’s trump suit, passing is often the right course at the 2-level or higher.  I am not sure at this vulnerability I would have had had the nerve to pass, given that I was not confident we could set the contract two tricks.  But in this particular case, had we played the same defense, the result would have been down two doubled for a cold top.    If I had decided to bid 3♦ instead, we would have at least gotten an average board.  Either result would have been better than a cold bottom.

What do you give up if you play this double in pass-out seat to be a D.S.I., and not penalty, double?  Really nothing.  If you would have otherwise been tempted to make a penalty double (holding ♠QJTx for instance), you might not set the contract.    Partner should have made a take-out double of his RHO’s 2 spade raise if he had a sound opening hand with his necessarily short spades (there are only 13 spades in the deck, after all).   If he doesn’t have sound opening values, your double may just give away the bad trump break and allow the opponents to make the contract through clever plays in the trump suit.  Of course, if partner does make a take-out double of his RHO’s 2 spade raise (showing full opening values), responder can pass for penalties holding  ♠QJTx and about 10 HCP overall and collect a big fat +500 or +800.

In the evolution of bridge bidding over the last 50 years, low-level doubles particularly have trended towards having a take-out, not penalty, meaning.  Certainly that is true for all 1-level doubles.   The D.S.I. double is just an extension of this idea:  doubles through the 3-level tend to be take-out oriented but will be left in more often because leaving the double in becomes a more intelligent thing to do at higher levels of bidding.

A note on the defense:  while my partner’s defense was excellent, it was not perfect.  Better to cash two hearts and then give me a heart ruff by leading her low heart, to keep from establishing the ♥10 in dummy.  That way, I can safely take the first diamond but not cash the 2nd — rather, I can shift to a club immediately before the diamond ♦Q becomes established.  This always sets the contract two tricks.  As we in fact defended, if declarer had guessed to “fly king” of clubs when I underled my ace, he would have made his contract, both the 10 and Q having been established for club pitches.  Bummer.

— Tom Hunt



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