Support Double

The support double is a double by opener to show 3-card support for responder's suit. It was originally invented by American expert Eric Rodwell.

The double is used when opener starts with one of a suit, responder makes a new suit reply, and the next player interferes. The goal is to help you distinguish 3- and 4-card trump support, which can be invaluable. Here's the type of bidding accident that the support double can prevent:

		West			East
		KT			65
		AJ8			KQ952
		K97			A852
		QT963			KJ
		West     1 1NT		North     Pass 3	East     1 3NT	South     1 All Pass

East's 1 only promises a 4-card suit. So when South overcalls 1, West's options are limited. Pass feels conservative and 2 would promise 4-card support, so she settles for 1NT given her balanced hand and spade stopper.

Now East is stuck over 3. He wants to probe for 3-card support but can't. Consequently, he guesses to bid 3NT instead of doubling for penalty. Unfortunately this fails when the opponents lead a spade to knock out West's king, and then regain the lead with the A to run spades.

This is where support doubles come into play. Imagine that West could have doubled 1 to show 3-card support:

West     1 Dbl

North     Pass 3

East     1 4

South     1 All Pass

What a difference in the auction. West's double shows exactly 3 hearts. East, now aware of the 8-card fit, simply bids 4, making.

What do East-West lose by using a support double? A natural penalty double of 1, which is a paltry price to pay. As seen in the example above, the value of differentiating 3-card and 4-card support can be a game swing.

Some fine print when support doubles apply:

1. Opener and responder must have bid two different suits at the 1-level.
2. Responder must have bid a major.
3. Support doubles are on through 2. However, some partnerships limit this to 2 so that responder can always sign off at the 2-level.
4. There is no point count minimum or maximum to make a support double.
5. Making a support double is opener's first priority. This is more important than rebidding no-trumps to show an enemy stopper, rebidding a 6-card suit, bidding a new suit, etc. Opener denies 3-card support if she makes any call other than double. (Excluding natural raises of responder's suit, of course.)
6. If the opponents' interference is in the form of a double, a redouble by opener shows 3-card support. This is called a support redouble.

And now, some more fine print when support doubles might NOT apply:

1. Support doubles are off when opener or responder has bid no-trumps.
2. Support doubles are also off when advancer (opener's RHO) bids a strong no-trump.
3. Opener isn't necessarily required to make a support double. She may be allowed to pass holding 3-card support with a weak balanced hand. This is open for partnership discussion.

This is a lot to digest, so hopefully the ensuing examples will help.

West     1 Dbl

North     1

East     1

South     2

Double shows exactly 3 spades. It does not matter 1) whether North has bid or not, or 2) whether North-South bid the same suit.

West     1 2

North     1

East     1

South     2

2 guarantees 4 hearts. West would have doubled holding only 3-card support.

West     1 2

North     Pass

East     1

South     1

2 shows 6+ clubs and denies as many as 3 hearts. Making a support double is opener's first priority.

West     1 Redbl

North     Pass

East     1

South     Dbl

Support doubles can also be used if the opponents double responder's bid. In this case, West makes a support redouble.

West     1 Dbl

North     Pass

East     1

South     1NT

If South's 1NT is natural and strong, then West's double is for penalty. A support double would risk landing in a 4-3 heart fit after South has advertised strength with a heart stopper.

West     1 Dbl

North     1

East     1

South     1NT

...If you really want to get nuanced, however, you can play support doubles when responder guarantees a 5-card major and the next player bids a strong 1NT. Here East has promised 5 spades because he could have made a negative double with only four. Depending on your faith in the Law of Total Tricks, it might make sense to bid up to the 2-level with 8 trumps.

Weak Rebids

In each of the following auctions, responder has roughly 6-10 points. Opener is allowed to keep bidding with extras.

	West AK7 9543 9 AK876		East QJ532 A92 Q65 T9
	West     1 Dbl1	North     1 Pass	East     1 22	South     2

¹ Support double
² 6-10 points, possibly only a 4-card suit.

	West QT8 753 A9 AQJ76		East A87 A942 T875 T9
	West     1 Dbl1	North     Pass Pass	East     1 1NT2	South     1

¹ Support double
² 6-10 balanced points, only 4 hearts. Tends to promise a spade stopper.

	West JT85 Q53 A92 AQJ		East 9 A942 K8753 T95
	West     1 Dbl1	North     Pass Pass	East     1 22	South     1

¹ Support double
² 6-10 points, only a 4-card major. Promises 5 diamonds. Opener can pass or correct.

Compare this next auction to the previous one. A new suit rebid carries a different meaning when responder holds both majors.

	West KQJ KQJT AQ42 84		East A8763 A942 5 T95
	West     1 Dbl1	North     Pass Pass	East     1 22	South     2

¹ Support double
² 6-10 points, showing 5 spades and 4 or 5 hearts. Here responder is checking for a 4-4 fit, which might play better than a 5-3 fit.

	West JT85 Q53 A9 AQJ7		East 9 A942 K753 T954
	West     1 Dbl1	North     Pass Pass	East     1 22	South     1

¹ Support double
² 6-10 points, only a 4-card major. Promises 4+ card support for opener in case clubs are a better fit. Note that East is too unbalanced to bid 1NT, while 2 would promise a 5-card suit.

	West AQ K53 KJ754 976		East T983 QT76 Q62 AJ
	West     1 Dbl1	North     Pass Pass	East     1 22	South     2

¹ Support double
² 6-10 points, only a 4-card major. Unlike the prior example, this only promises 3+ card support for opener at the 2-level. Note that East can't bid 2NT which would be invitational.

Invitational or Better Rebids

If responder jump-rebids her suit at the 3-level, then she has 10-12 points with a 5+ card suit. Opener is invited to bid game.

	West AQ K53 KJ754 976		East T98 AQJ84 A62 J5
	West     1 Dbl1	North     Pass Pass	East     1 32	South     2

¹ Support double
² 10-12 points with 5+ hearts. Invitational to game.

If responder rebids or jump-rebids 2NT, then she has 10-12 balanced points and only a 4-card suit.

	West AQ K53 KJT54 976		East 432 QT84 A62 AQ4
	West     1 Dbl1	North     Pass Pass	East     1 2NT2	South     2

¹ Support double
² 10-12 balanced points, invitational to game. Shows only 4 hearts.

If responder jump-raises opener's suit, then she shows 4+ card support with only a 4-card major. This tends to imply the lack of an enemy stopper; otherwise responder would have bid 2NT.

	West AQ K53 KJT54 976		East J32 AQJ4 A962 T2
	West     1 Dbl1	North     Pass Pass	East     1 32	South     2

¹ Support double
² 10-12 points, 4+ card support with only 4 hearts.

If responder makes an artificial cue-bid, then she has a good 12+ points. This is forcing to game.

	West K53 AQ KJT54 976		East AQJ42 K32 A62 T2
	West     1 Dbl1	North     Pass Pass	East     1 32	South     2

¹ Support double
² Game-forcing, may only have 4 spades.

Rodwell, Eric. Bidding Topics. Louisville, Baron Barclay Bridge Supply, 2017.