Negative Double

After partner opens on the 1 level and RHO bids, a double by responder is a Negative Double (ND).

Standard Negative Doubles:

The following is based on Larry Cohen's web site:

A negative double promises both majors have 4+ when the overcall is 1.
With only one 4-card major, just bid it.

When the overcall is 1, a negative double shows exactly 4 spades (no more, no less) and doesn't promise any other suits.

In Aces 03-03-2020, Bobby Wolff says to double with K984 Q9 QT543 95: Preempting 3D has more to lose than gain.

In May 2018 Bridge Bulletin, p.57, Marty Bergen says not to make a negative double over RHO's one-of-a-major overcall when you have a strong 4+ in RHO's suit, even if you have 4 of the other major..

Weak, Distributional Negative Double:

In ACBL's It's Your Call was the hand - AK74 KQT954 J94 with the bidding 1-(2)-D-(P).

Eleven of the 19 experts bid 3 and 5 just bid 2. Bidding 3 was considered "going slow" with this hand. The reason for not jumping to 4 is that:

Partner may or may not have four hearts

Partner could have the one-suiter in spades, in which case we are too high already.

If North made a one-suit negative double with long spades, [3H] may not fare well.

With KQTxxx-Qx-Jxx-xx, [doubler] would make a negative double, planning to bid spades next.

Others pointed out that partner's assumed spade values may be wasted opposite this hand's spade void:

Partner doesn’t have to have hearts. I’m not sure this hand is worth a jump anyway, as the spade void is likely to be a wasted value, and the club holding is a liability.

Partner might have a significant portion of his resources in spades.

The hand 87543 9 AQJ653 2 with bidding of 1 - 3 - ?? came up in a local pairs event.

The concern was that making a negative double would deny diamonds since it normally would show spades and clubs.

One of the top players in the club said that a negative double is the correct bid with the primary goal being to get partner to bid spades, and that if partner bids clubs, we could pull it to diamonds.

Doomsday Double 

Based on Mel Colchamiro's article, The Death of the Doomsday Scenario on pages 24-25 of the May 2021 ACBL Bridge Bulletin. (If you don't save back issues of the Bulletin, you can read them on the ACBL website.)

When both majors are unbid... 

A Negative Double means one major has exactly 4 cards and the other has 4 or fewer. 
Bidding a major shows 5+ cards.

After a ND, if opener has a 4-card major, he should bid it even though doubler may be short in the suit, in which case doubler will bid something else, such as raising clubs.

BidBase calls this Negative Double: Doomsday so that all the related bids can be activated or deactivated with one double-click to choose either treatment.

So playing Standard ND, when responder bids a major, opener doesn't know if responder has 4 or 5+ of the major bid, but when playing Doomsday Doubles, when responder doubles when both majors are unbid and opener has 4 of only one major, he can't be sure that doubler has 4 of the same major.

It would seem that DoomsDay Doubles are just trading one unknown for another, though you should read Mel's article to decide for yourself.

Also see Jerry Helm's column Ask Jerry in the Nov. 2020 Bulletin, p.47. Jerry says that after1-1, responder should ignore the 1 and bid whatever he was going to bid.

Jerry continues: "A major-suit bid here does not promise or even imply more than a 4-card suit... A double guarantees exactly four cards in each major." After a 1 overcall, a bid of 1 guarantees 5+ spades since an ND would show exactly four, according to Jerry.

If responder's RHO overcalls on the 2 level (e.g.: 1-2), a bid of 2 guarantees a 5-card suit or longer.

With a hand shape like 2=4=5=2, an ND shows at least one 4-card major and a place to play if opener doesn't have 4 of that major -- diamonds in this case.

Negative Double vs Takeout Double: 

A Takeout Double [e.g.: 1-Dbl] only promises 3 cards in the unbid major, but a Negative Double [1-(1)-Dbl] promises 4 cards in the unbid major.

Why the difference?

Takeout Double: 

You normally have shortness in only the opponent's suit and support for the 3 other suits. An exact 4-4-4-1 distribution is much less common than 4-3-5-1 or 4-4-3-2 thus if 4-4-4-1 were required, you would rarely get to make a takeout double. 
You know nothing about partner's hand. Even if you only have 3 of an unbid major, partner may have 5+ of that major or if he only has 3, he is more likely to have a long minor for which you have support or he may have the opponent's suit and can bid notrump.

Negative Double: 

An ND shows shortness in two suits, making it much more likely that you will have 4-4 or more in the unbid suits. 
If partner opened a minor, he is much less likely to have 5 cards in the unbid major, so if you make an ND with a 3-card unbid major, about the best you can hope for in that majaor is a 4-3 fit.

When is an ND not an ND?. 

When the bidding starts 1-(4), is a double an ND or is it for penalty or a Nebulous Double (extra HCP with no clear direction)?. 
Most people play that such doubles are Negative through 4, meaning that a double after, say, 1-(4) is for penalty.. 
The important point is that whatever level your partnership decides on, a high-level ND in that range has the same requirements as a 1-over-1 ND, including 4-4 majors if they are both unbid; otherwise, you are not making an ND as shown on your convention card 

HCP requirements for a negative double: 

• 6+ HCP if opener may bid an unbid major on the 1 level.
• 7+ HCP if RHO overcalled 1 or 2
• 8+ HCP if RHO bid 2
• 9+ HCP if RHO bid 2.
• 10+ if RHO bid 3
• 11+ if RHO bid 3.
• 12+ if RHO bid 3 .

Examples: (from a different source using slightly different HCP requirements) 

1-(1)-Dbl = 6+ points and 4+ Hearts and 4+ Spades.
1-(1)-Dbl = 6+ points and 4 Spades. With 5+ Spades and 6+ points, responder bids 1
1-(1)-Dbl = 9+ points and 4 Hearts. With 5+ Hearts and 11+ points, responder bids 2
1-(2)-Dbl = 11+ points and 4 Hearts.
1-(4)-Dbl = 13+ points, 4 Spades and 4 Hearts.

If partner makes a preemptive opening bid, including Weak Twos, and the next player bids, a double by opener's partner is a penalty double, not a negative double.

To what level is a double negative rather than penalty?

Options:

1. In SAYC, doubling of any bid through 2 is negative.
2. Many, if not most, people now play negative doubles through 4.
3. Larry Cohen says a double should be negative "through infinity".

BidBase has entries for all three, so in the BidBase Editor, you will need to choose which you prefer.
However, picking which you want is kind of tricky because the entries are not really variations of Negative Doubles. Instead, they build on each other.

1. All Negative Doubles are bid the same through 2,
2. At 3 doubles become penalty doubles for option 1 while options 2 and 3 have the same criteria for negative doubles which we will call Negative Doubles: 3C and Up.
3. At 4, option 2 starts making penalty doubles while option 3 continues to make negative doubles.which are called Negative Doubles: 4H and Up

If you prefer some other level, you will need to make entries for them in BidBase.

When responder has a big hand:

If responder has game-forcing values, it can be hard to get that across when a double can show anything from 6 to 20+ points and the bidding has gone something like 1-(2)-D-(P)-2. You have to come in on the 3 level to show your 4-card suit, even with a minimum. What do you do with a really big hand and no support for opener?

One solution is to use a cuebid of RHO's suit (3 in this case) instead of double to show a game-forcing takeout.
The only problem is that such a cuebid is usually used to show a limit raise or better in opener's suit.
I don't know which is better and searches on the Web haven't turned up anything helpful.

Opener's bids after a Negative Double:

As noted above, doubler may have a minimum of 6 HCP, 9, or 11.
The points required for opener's rebids will be shown as # / # / # to match those minimums.
Example: 19 / 16 / 14 where 19+6=25=game, 16+9=25, 14+11=25.

1. Force with 19+ / 16+ / 14+ points,
   a) splinter in a singleton or void with 4+ support in doubler's major, else
   b) bid game in doubler's major with 4+ support
   c) jump in your suit with a good 6+ cards, else
   d) cuebid LHO's suit.
2. Invite with 16+ / 14+ / 12+. Doubler accepts with 9+ / 11+ / 13+ points.
   Jump bid one of doubler's suit with 4+ support, else
3. Bid one of doubler's suits with at least 4-card support, else
4. Pass for penalties with 4+ cards and 3+ points in LHO's suit and 2.5+ outside quick tricks, else
5. Without support for doubler and with stoppers and/or length in LHO's suit,
   a) Bid 3N with minimum combined points for game or
   b) Bid 2N to invite or if you must bid on the 2 level, or
   c) Bid 1N.
6. If none of the above, you can rebid your suit with 5+ cards and a minimum.

Opener's rebid when his RHO intervenes:

Opener is not required to bid again. If overcaller's partner bids, opener will normally bid one of his partner's suits with 4+. With <4 and no other good bid, opener can pass it back around to responder.

Opener's reopening double when responder passes rather than doubles:

Since a double is for takeout, the only way for him to double RHO's overcall is to pass and hope that opener will make a reopening double.

Opener should be particularly alert to this possibility. One clue is if opener is short in his LHO's suit. He should also have a hand suited to defense since he will be trying to defeat a low-level contract.

Vulnerability is a factor since a double of non-vulnerable opponents in a low-level contract will rarely make up for a missed vulnerable game.

If responder trap passes with a good hand and opener reopens with a suit bid rather than with a double, responder must make a forcing bid (e.g.: cue bid, jump bid) to distinguish from hands in which he passed with a bust. Opener normally must pass after a non-forcing bid in this situation.

A question remains of how many points responder should have to make a trap-pass rather than to go for game. Clearly, with less than 10 HCPs and most of them in RHO's suit, game is less likely and a penalty double, therefore, more attractive.

Western Cue Bid:

When opener does not raise doubler's suits and has a balanced hand but no stopper in overcaller's suit, a Western Cuebid is asking for help in that suit for bidding notrump.

Example:

1-(1)-D-(P)
2-(P)-2 (Source: Richard Pavlicek - bottom of the page.)

Doubling a 1N Overcall:

When partner opens 1 of a suit and RHO overcalls 1N, a double is for penalty, not showing the unbid suits.

The doubler is showing 10+ HCP. Opener can still choose to bid if he has "any long suit or any shapely two-suited hand. His failure to double denies a good hand [and thus] is non-forcing." - Jerry Helms, September 2019 ACBL Bridge Bulletin, page 48.