Support Doubles

The double says nothing extra about strength. Opener can hold a bare 12 points or a hand worth 18, and a strong opener doubles first and bids again later. It also says nothing about the overcaller's suit, so opener cannot double the overcall for penalty while playing support doubles.

Three things have to be true. Opener has opened one of a suit, responder has bid a major at the one level, and opener's right-hand opponent has made a call before opener's rebid. That call can be a suit overcall or a takeout double.

• Up to two of responder's major. The usual limit is an overcall no higher than two of responder's suit. After 1♣ - 1♠, a 2♥ overcall still allows a support double because 2♥ is below 2♠. After 1♦ - 1♥, a 2♠ overcall is above 2♥, so opener's double is not a support double. Most pairs treat that higher double as showing values, and some as penalty. Agree which.
• After a takeout double, redouble. When RHO doubles responder's major, opener's redouble shows exactly three cards in it and a raise shows four. The traditional meaning of the redouble, a strong hand, has to find another route.
• Majors only, usually. Most partnerships use support doubles only when responder has bid a major, since a minor-suit fit is less often where the side wants to play.
• When both opponents have bid. Many pairs also play opener's double as support in auctions such as 1♣ - (1♦) - 1♥ - (2♦) - X. It is a sensible extension, but check that partner plays it too.

Once the double is reserved for three-card support, every other rebid by opener denies three cards in responder's major. Responder can build on that.

Opener's pass does not show a weak hand. It can hide a decent hand that has no clear bid, often one with length in the overcaller's suit. Responder should hear it as "I have at most two of your suit" and act accordingly.

Responder now knows the exact fit. Holding four cards in the major, the side has seven trumps. Holding five, it has eight, and six gives nine. Responder rebids as if opener had raised with three cards, which in practice means the cheapest bid in the major with a minimum, a jump with invitational values and game with enough for game.

The difference between seven and eight trumps matters most when the opponents keep competing. By the law of total tricks, a side with eight trumps is usually safe at the two level and a side with nine can go to the three level. A 4-3 fit is fine at the two level and a poor place to be pushed higher. Responder with four cards in the major and a minimum usually lets the opponents play at the three level rather than bidding on.

Passing the support double for penalty is possible but uncommon. Responder needs a strong holding in the overcaller's suit, sitting over the bidder, and opener may have no tricks in it at all.

Opener gives up the low-level penalty double of the overcall. Holding four good cards in the overcaller's suit and no support, opener passes instead. Responder, short in the overcalled suit, can reopen with a double when the auction comes back, and in most partnerships opener can then pass it for penalty. Most pairs judge that the loss is small, because opener rarely holds a strong penalty double at the one or two level.

The support redouble has a similar price. The traditional strong redouble is gone, and a strong opener without three-card support has to show strength later, usually by bidding again at a higher level or by doubling the opponents later in the auction.

• Raising on three cards. Once the agreement is on, 2♥ after 1♣ - 1♥ - (1♠) promises four. Holding three hearts, double, even when the hand is a minimum.
• Passing with three-card support. A minimum opener sometimes passes to avoid saying anything. Responder will then play opener for at most two cards and may give up on the fit.
• Doubling the overcall for penalty. The double shows three-card support. Opener with length in the overcaller's suit passes and waits.
• Using it too high. After 1♦ - 1♥ - (2♠), the overcall is above 2♥, and opener's double is not a support double.
• Responder counting on four-card support. Responder holding a four-card major opposite a support double knows the side has seven trumps and should not compete above the two level on the fit alone.