Support/Cooperative Doubles

The "Support Double", developed by Eric Rodwell, is one of the most universal and useful conventions in tournament bridge.  I haven't seen the original definition but here is the basic idea:

Whenever you have opened in a suit, partner has responded at the one-level, and right-hand-opponent has bid such that you would be able to raise partner to the two level – then said raise will promise four-card (or more) support, while double will promise three-card support.

There are a number of questions that this opens up, however:

1. If you pass instead of raising or doubling, does this guarantee fewer than three-card support?
2. Do you need to have a minimum point-count?
3. What if partner already promised five cards in his suit, should you still double with three? if not, then what does double mean now?
4. While the original description precludes it, what if RHO made a jump?  Could we agree that it's still a support double?

Regarding the first point, Rodwell himself is on record as having said that if you have a weak hand, perhaps a third seat opener, and you wouldn't have made a three-card raise sans competition, then you aren't obliged to double (i.e. you can pass).  For the second point, a big factor is your 1NT range.  Support doubles are made on balanced hands probably 80% of the time.  So, if you play 12-14 notrumps, then you won't have a 12-14 balanced hand when you make a support double and thus will typically not be making a support double on a "dog".  Regarding the third point, I know many experts play that support double is still on if partner promises five cards, which can happen in the auctions 1♣ 1♥ 1♠ 2♥ X or 1♦ 1♥ 1♠ 2♥ X.  That has the advantage of simplicity.  My take on this is that it should not be a (strict) support double, but rather a cooperative double (I certainly wouldn't advocate playing penalty doubles in this situation).  I will go on to show that support doubles are essentially a particular species of cooperative double, so that there really isn't any difference in the two approaches.

My particular interest for this discussion lies in the fourth point.  I have recently come across a pair (I'm closely related to one half of this pair) that extends the range of the support double up to the three level when a jump intervenes.  Of course, it must show some extras.  Here's what it says: I'm one card short of being able to raise your suit directly, partner;  I have extra values;  I have a relatively balanced hand;  I'm relatively short in the opponent's suit.  This is precisely the definition of a cooperative (or do-something-intelligent-partner) double.  By the constraints of the game, I can hold only thirteen cards.  Let's say I already opened a suit, so that's four (or more) right there.  I've got three-card support for partner (now we're up to seven, plus).  I've only got six other cards (fewer perhaps).  If six of them were a second suit, I think I'd have no problem finding a bid.  If I had a five-card side suit, I probably wouldn't have a problem.  But what if my second suit is only four cards long and I've got, say, two cards in the enemy suit.  That's precisely when I need to be able to make a cooperative double.  Insufficient cards in our suits to have a clear call, extra points, and a couple of cards in the opponents' suit which will be helpful if partner decides to convert the double to penalties.  

East intended the double as a "support double" but this auction apparently hadn't been clearly determined in advance.  They eventually bid up to 6♣ (for 5 matchpoints out of 13) but missed the cold 7♥.  So, you see, whether you call it a support double or a cooperative (DSIP) double, it really amounts to the same thing.  At the two-level (the traditional domain of the support double), given that we might both have minimum hands, it makes sense to have the support double show exactly three.  But at a higher level, you might still make a cooperative double with only two card support for partner – but then you will have compensating strength.

Thus, the cooperative double and the support double stand together with some other conventions that deny the ability to show primary support of partner's suit and/or request partner to show secondary support.  Examples include fourth-suit-forcing, new minor forcing, the forcing notrump.

The reason for all this difficulty of course, is that, in a constructive and forward-going auction, we generally do not like to raise with three (in case partner has only four) and we tend not to rebid suits unless we have six (in case partner has only two).  This leaves the finding of a 5-3 fit one of the trickier aspects of bridge.  The support double and its more general cousin, the cooperative double, are one of the tools that can help us in this quest.