Lead restrictions following insufficient bid
N E S W
P P 1S P
1N x 2C P
2S P P x
P 2D
East makes an insufficient call of 2D. It is replaced with a Pass and 2Sx become the final contract.
Declarer can prevent West from leading any suit not specified in the lagal auction (Law 26B).
Which suit(s) have been specified by East's original double, a take out double of Spades?
Comments
No suits have been specified, so any (one) suit can be prohibited
I think this is going to depend on E/W's system. Many pairs play that a takeout double of spades always has hearts (in fact, some pairs play that the double primarily shows hearts and doesn't guarantee length in other suits) – in that case, N/S probably can't prohibit a heart lead. Many other pairs play that a takeout double is focused on all the remaining suits, in which case there probably hasn't been enough information specified about any particular suit to prevent a lead restriction being placed there.
Law 26B is a little difficult to use because it uses the word "specified" without clarifying what it means, there are multiple plausible meanings, and the word is used inconsistently in the Laws. The definition of "denomination", for example, implies that a bid specifies the suit or notrumps that is actually called, e.g. in that definition, a response of 2!d to 1NT that shows hearts is "specifying" diamonds (this is used to define the call as artificial, because the bid denominates diamonds but shows willingness to play in hearts). Law 27B, on the other hand, seems to use it to describe which suits are actually being shown by a call.
There is Commentary for Law 26B, which suggests that a suit is exempt from a lead penalty if "the legal auction [has] imparted suit-specific information (i.e., information about the actual holding in that particular suit)". This still doesn't clarify matters much, though (although it makes it clear that "specified" is being used to talk about what the bids show, not what the bids are). There's an interesting example there that states that a bid showing 4=4=1=4 shape exactly specifies all four suits (because it shows length in three suits and shortage in one), and therefore (if part of the legal auction) prevents any lead restriction being implied.
There doesn't seem to be any guidance about "how much" information about a suit is needed, though. I generally play that a takeout double of spades (as would be the case after (1!s), P, (1NT,) X) guarantees at least three hearts, and will usually have four. Is that enough information about hearts to prevent a lead restriction being placed there? What about pairs for which the double always has four hearts, or pairs for which doubling on three hearts is common? It seems to me that the Law in question doesn't give a clear enough test for which suits can be lead-restricted.
I'd want real evidence before accepting that a double shows hearts. What do people who claim to play this method do with:
x
AKx
AKQx
Jxxxx
or
AKx
AQx
AKxx
Qxx
or
xx
AK
AKQxxxx
Ax
I agree that the sequence 1S X does not necessarily show (specify) any suit for the examples Gordon has given.
However in the OP East has passed initially. Does this not make it much more likely that they have a Heart suit?
It's based on what the call shows, not what the hand is likely to contain.
For me, the third of Gordon Rainsford's hands is an artificial 3!s call (which lets me find out whether partner has a spade stopper, and gives me the option to show a slam try in diamonds). The other two are awkward to bid – I might double with the first (as my double doesn't promise four hearts, only three), but a double seems unlikely to help with the second hand. If the opponents were vulnerable, I'd probably pass and hope that the penalty is bigger than our game (or that they bid clubs – I can double that); my experience is that trying to penalise 1NT with a double is almost impossible (it gives the opponents more bidding space to figure out where to run, and then you're stuck trying to work out whether to double the resulting contract or to bid constructively), so if going for a penalty, you have to pass. Otherwise, I guess I have to bid 3NT or pass (or 2NT if it isn't artificial); 3NT won't make if everyone has their bid, but it's basically impossible to hold that hand unless someone has psyched, so it may well be worth playing for the psyche.
My experience is that doubling because the hand is too good to do anything else tends to work about as badly as just doing the anything else, though – partner will always play me for the unbid majors, and this often leads to silly contracts if I don't have them.
(I also agree with ManchesterRambler that most pairs have stricter shape requirements for doubles by passed hands. With the exception of positions in which a double would be artificial, It's very rare (perhaps impossible? I can't think of any examples offhand) for me to double in direct seat as a passed hand without 4 cards in every unbid major and (if there is one) at least one unbid minor – if I had any other sort of hand worth a direct seat double, I would have opened it.)
I guess all this is just an argument that, ideally, we'd have some sort of comprehensive system book for every partnership showing the meaning of every possible sequence. (These are harder to compile than you might think; it's generally only done for bots, and even then the system tends to contain many nonsensical sequences. For example, the bots on BBO have a sequence which, according to the auto-alerts, shows a hand containing more than 13 cards.) What sources do define a takeout double, though, typically set a lower limit of 17-19 points for a double that doesn't have at least 3-card (and preferably 4-card) support for every unbid major – given that any 17-count would be opened, it therefore seems to me that a takeout double by a passed hand does indeed guarantee ("show") at least three cards in every unbid major.