Bridge bidding -- DONT Convention Summary
Introduced by Marty Bergen in Bridge Today (Sept./Oct. 1989 issue; pp. 23-29)
The DONT convention ("Disturb the Opponents' Notrump) is used in the direct or balancing seat after an opponent opens a strong notrump (14+ HCPs). It can also be used over 2NT openers.
Overview of DONT actions
Double = Unspecified one-suiter; relays responder to 2C.
2C, 2D, 2H = Two-suiter (usually at least 5-4); shows the suit named plus a higher-ranking suit.
2S = Spade one-suiter.
2NT = Major-minor two-suiter (6-5 or better), monster hand. (This relays partner to 3C, over which opener identifies his two suits via a fairly complicated code. See the original Bridge Today article for details on these follow-up bids.)
3C, 3D, 3H, 3S = Long suit (usually 7+ cards), preemptive.
3NT = Major two-suiter (6-5 or better), monster hand.
One-suited hands (Double or 2S overcall):
Double relays partner to 2C to let the doubler show his suit. The doubler can then pass (if his suit was clubs) or bid 2D, 2H or 2S. If the doubler holds a strong hand with game interest, he can jump to 3 of his suit.
Bergen warns that the since the doubler could be light in high cards, partner should "never" leave the double in. However, partner is not forced to take the 2C relay if he has his own suit (a 6-card suit or good 5-carder), especially when he holds extreme shortness in one of the unbid suits. One of the examples Bergen gives is
Jxxx
x
KQJ10x
xxx . Instead of taking the relay to 2C (over which partner will most likely bid 2H), he would bid 2D over partner's double.
After the overcaller shows his suit, partner can raise to show a fit. Raises of minors tend to be preemptive; raises of majors show a mild game invitation. To show a fit and a stronger game invitation, partner bids 2NT.
A 2S overcall is one of two ways to show a spade one-suiter (you can also double first, and then rebid 2S). To distinguish between the two sequences, you can adopt one of these sets of agreements (depending on your partnership preference:)
A direct 2S overcall shows minimum strength. Double-then-2S shows extra high-card values and more defense.
A direct 2S overcall shows a "true" one-suiter with longer, stronger spades. Double-then-2S shows only a 5-card spade suit and/or a hand that may be suitable for play in other suits. Since the double gives responder room to show his own suit, the double-then-2S auction tends to show a more balanced hand.
Two-suited hands (2C, 2D, 2H, 2NT or 3NT overcall):
After a 2C, 2D or 2H overcall, the meanings of partner's bids are:
Pass = He's content to play in the suit bid. He'll usually have shortness in one or more of the higher-ranking suits.
Bid of the next cheapest suit (i.e., 1NT - 2C - Pass - 2D) = He prefers to play in your other suit and wants you to bid it (or pass if his bid is your suit). Partner will usually have at least 3-card length in all higher-ranking suits. If partner asks for your other suit and then rebids 2NT after you show it, it's a strong game invitation in your second suit.
Bid of a new suit that is not the cheapest suit (1NT - 2C - Pass - 2H or 2S) = Natural, showing his own 6-card suit or strong 5-carder.
A raise of your minor-suit overcall or rebid tends to be preemptive.
A raise of your major-suit overcall or rebid is mildly invitational. 2NT shows the strong invitation.
2NT (rare) = A strong game invitation that asks you to bid your other suit at the 3-level (or 4-level, if your second suit is a major and you are strong enough to accept the invitation). Partner will always have excellent support for all higher-ranking suits.
In general: If you're responder, assume that partner's second suit is probably the one where you have shortness, and remember that he may be only 5-4 in his suits. If partner overcalls 2C and you hold
As Bergen notes, if partner overcalls 2D and you hold
Over opponents' interference
If the 1NT opener's partner bids or doubles after your DONT overcall or double, your partner should never try to "guess" what your unnamed suit is. The only way to get the DONT bidder to show his unnamed suit is to double or redouble.
After your DONT two-suited overcall and an intervening bid by the opponent, the meanings of your partner's bids are:
Pass = He's content to play in the current contract.
Redouble (over the opponent's double) = He prefers to play in your second suit and wants you to bid it.
Double (of a natural bid) = He wants you to bid your second suit. This double shows some high-card strength and tolerance for all unbid suits.
Double (of an artificial bid) = Lead directing. Some players forego the lead-directing definition and agree that a double of an artificial bid is the same as the double of a natural bid -- it shows values and encourages partner to bid his unnamed suit.
Any suit bid = Natural, showing his own long suit.
Defending against DONT overcalls and doubles:
If you open 1NT and your opponent makes a DONT bid or double, Bergen's system for partner's responses is:
Over any DONT overcall or double: Texas transfers (if you normally play them) are "on".
Over a double (one-suiter): Play "front of the card" (your normal response system with Stayman, transfers, etc.)
Over a 2C overcall: Play "front of the card" (transfers, etc.), except use double for Stayman.
Over a 2D or 2S overcall: Treat either as a natural one-suiter. (Double is penalty, Jacoby transfers are "off", Lebensohl sequences are "on".)
Over a 2H overcall (major two-suiter):
Double = "Cards" (around 8+ pts.) and at least 2 hearts.
2S = Minor-suit Stayman (weak or strong hand with both minors).
2NT = Lebensohl (Relays opener to 3C; responder can then sign off in a minor or show a good hand with stoppers).
3C or 3D = Natural and invitational.
3H or 3S = Singleton in that suit, game-forcing.
3NT = To play, but with no major-suit stoppers.