RESPONSES TO ONE-LEVEL SUIT OPENINGS

BIDRESPONSES TO OPENING 1CRESPONSES TO OPENING 1DRESPONSES TO OPENING 1HRESPONSES TO OPENING 1S
PassVery weak (0-5 points), no desire to shut out opponents.
Double of suit overcallTake-out if below 4S. To make a takeout double of an overcall and then pull partner's response when they do take it out is non-forcing with at least a five-card suit, since an immediate bid would have been forcing. (The logic is different after 1NT openings.)
Double of no-trump overcallPenalties
Redouble10+, wants to double for penalties, often a misfit. During the subsequent auction, the partnership has one standard takeout double "in the bank". This is in order to distinguish between a hand that simply wants to compete (will pass and wait for partner to make a takeout double) and one with game-forcing strength (will bid directly, forcing).
Minimum cue bid of overcall where the partnership can still stop in part-score; i.e. below 3 of opener's suitUnassuming Cue-Bid, with trump support and intermediate points. (Might occasionally be a preliminary move on a much stronger hand.)
1Dnatural, one-round force
1Hnatural, one-round force
1Snatural, one-round force
1NT after overcallNatural, constructive, about 7.5-10 points and denying four cards in any unbid major. Good holding in the opponents' suit, preferably at least one and a half stops.Natural, constructive, about 7.5-10 points. Good holding in the opponents' suit, preferably at least one and a half stops.
1NTA balanced hand with club support that doesn't have a four-card major, is too weak for 1C 2C and doesn't want to bid 1C 3C.single-suited in clubsUnable to make any other response, says nothing about shape
New suit at 2 level after 1NT overcallNatural, non-forcing and to play, because a hand with game-going strength would have doubled.Natural, non-forcing and to play, because a hand with game-going strength would have doubled. Auctions like 1S (1NT) 2C from a passed hand no longer show a weak hand with three-card trump support because that's too dangerous after the 1NT overcall, while intermediate hands will just double.
2C4+ clubs, game-forcingGame-forcing, assumed to be 4 cards but occasionally a waiting bid.
2C if passed hand (uncontested auction)Exactly 3 diamonds, values to raise to the two level. Also denies a four-card major, so must have a natural club suit.
2C if passed hand3-card support for partner, 2-level values and no better bid available. In an uncontested auction, denies a spade suit. This still applies after a suit overcall or a double, but after a no-trump overcall it's natural and non-forcing, with clubs.3-card support for partner, 2-level values and no better bid available. This still applies after a suit overcall or a double, but after a no-trump overcall it's natural and non-forcing, with clubs.
2C after suit overcallExactly 3 diamonds, values to raise to the two level.
2DGame-forcing, assumed to be 4 cards but occasionally a waiting bid.
2D if passed hand3-card support for partner, intermediate points and no better bid available. In an uncontested auction, denies a spade suit. This still applies after a suit overcall or a double, but after a no-trump overcall it's natural and non-forcing, with diamonds.3-card support for partner, intermediate points and no better bid available. This still applies after a suit overcall or a double, but after a no-trump overcall it's natural and non-forcing, with diamonds.
2HGame-forcing, 5 hearts
2H if passed hand3-card support and a five-card heart suit, intermediate points. This still applies after a suit overcall or a double, but after a no-trump overcall it's natural and non-forcing, with hearts.
Raise to 2Inverted Minor, 4+ trump support, denies a five-card major, forcing to 3m, 10-ish points or stronger.Weak, with trump support. If only three, had no better bid and in particular didn't much like the look of any of the less marginal responses (i.e. 1NT).
Raise to 2 after overcallWeak, with trump support. If only three, had no better bid.
Raise to 2 after doubleWeak, promises no strength at all
2NT11-12, balanced, would have raised a weak 1NT to two. Denies a four-card major and four of partner's suit, so by inference must have at least four of the other minor.11-12, balanced, would have raised a weak 1NT to two. Denies a four-card major. This promises precisely a doubleton in partner's suit if a passed-hand 2D response had been available to show intermediate strength with three-card trump support.11-12, balanced, would have raised a weak 1NT to two. Denies four-card spade support. Also promises precisely a doubleton in partner's suit if a passed-hand 2D response had been available to show intermediate strength with three-card trump support. Any continuation in an uncontested auction is game-forcing.
2NT after doubleIntermediate jump raise in partner's suit. (Might occasionally be a preliminary move on a much stronger hand.)
2NT after overcallNatural, constructive, about 11-12 points. Good holding in the opponents' suit, preferably at least one and a half stops.
Jump shiftStrong six-card suit, 16+ points. Still applies after any intervention except a 1NT overcall.
Jump shift by passed hand or after 1NT overcallFit-Jump, two-suited, at least 5-4, trump support for partner. Forcing and normally shows an 8-loser hand or so, without enough strength to go to game.
New suit response from a passed hand above 2 of opener's suit (after opponents' intervention)Whatever the same bid would have meant without the intervention, e.g. pass (pass) 1C (1S) 2H is a fit-jump in hearts, just as it would have been without the overcall.
Jump raiseInverted Minor, 4+ trumps, denies a four-card major, weak. More informative than the equivalent Inverted Minor raise of a 1D opening bid, since the existence of the 1C 1NT alternative (also showing a club fit) means that partner has actually chosen to pre-empt instead of merely being forced to jump against their will by the bidding system.Inverted Minor, 4+ trumps, denies a four-card major, weak4-card support, intermediate (10 points or so)
Jump raise to 3 after interventionPre-emptive. A redouble or an Unassuming Cue Bid is the bid to show an intermediate raise.
Jump cue bid after overcallSplinter
Unnecessary jump shift up to Splinter LevelSplinter, denying a 4 card major. If the splinter is in a major, then by inference must have at least nine minor-suit cards. However if the splinter is in the other minor, then must have at least six-card trump support in a 6331 hand.Splinter, agreeing partner's trump suit and showing a small singleton or void. Splinters are normally game-forcing, but if two of them were available then the lower is merely invitational, e.g. 1C 1S 3D/4D are both splinters, since 1C 1S 2D would have been a reverse.
3NTstrong no-trump (i.e. balanced 15-17) with four-card trump support.
Raise to 4mMinorwood
Game raise (opponents silent)Shows shape rather than points, might be pre-emptive.
Game raise (contested auction)To play.
Jump shift to Blackwood LevelExclusion Blackwood
Jump shift to Grand-Hunting LevelComplete two-suiter. If the partnership had previously bid more than one suit and so there's ambiguity about which suits are being promised, then the other one is the first-bid suit of the player who just jumped.
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Copyright 2015 Finn Clark.