The 12 Habits of Highly Effective Bidders   (November 2013)

10.  They allow their opponents to make mistakes. 

Judging when to make a penalty double is one of the most difficult aspects of bridge bidding. Bringing partner in on the decision can make it easier, and that's an advantage of DSI doubles ("Do Something Intelligent"). They allow you to show a hand that has good defense and offense, and let partner decide whether he wants to declare or defend.

In practice, most DSI doubles are intended mainly as takeout, with passing the fail-safe option. That works fine in many types of auctions, but it's still important to retain the pure penalty meaning of some doubles. Here are some auctions where partner's double "sounds like" it could be DSI, but is best played as penalty. 

           LHO     Partner     RHO       You   

  (1)                     1H           DBL       RDBL
             Pass       Pass         1S           Pass
             Pass       DBL        Pass          ?      

  (2)                                                   1C
             1H          1NT        2H          Pass
             Pass       DBL        Pass          ?      

  (3)       1S          DBL       Pass        2H
             Pass        Pass        3D          Pass
             Pass       DBL        Pass          ?      

  (4)                                                  1NT
             2C *         Pass        2S        Pass  
             Pass          DBL      Pass        ?

               * (majors)

(1) is deceptive because the auction is so low, but in standard bridge, this double is 100-percent penalty. The redouble sets up a situation where all subsequent doubles are penalty. You don't have to leave it in, but if you have a hand such as J4   102   AQ72   KJ762 , you should expect a big score, especially if they're vulnerable.   

Double tends to be DSI in low-level auctions where the opponents have a fit, but not always. In (2), partner already showed strength in hearts and denied interest in other contracts. He's not changing his mind now. 

The same idea applies in (3). Partner showed diamonds when he made his first takeout double. He can't now be making a takeout double of a suit where he already showed length.

A common agreement is that if we open 1NT and an opponent overcalls, a double by either of us is takeout if it's under the hand that has shown length in the suit. It's penalty if the doubler is sitting over that hand. In (4), your LHO is the hand with spade length, so partner's double is penalty.

Many of these double dilemmas can be worked out by thinking through the auction and the types of hands partner might hold. Here are some other guidelines for DSI doubles:

   2013   Karen Walker