Blue book 7C 1B
The recent changes to this section appear to ban the assumed fit pre-empt style of opening 2 of a suit to show a weak hand with 4+ in that suit plus another unknown 4+card suit for example a 2D opening showing 4+diamonds and 4+cards in a unspecified major.
However below are some of the options where you are allowed to open 2D showing a weak hand
4+diamonds and 4+spades
at least 4-4 in the majors
5+diamonds and 4+cards in a unspecified major.
5+cards in any suit other than diamonds
I was wondering the rationale behind this as I played the 4+diamonds/4+major bid for a while and it didn't seem too hard to defend against (certainly not much different to the other bids above that are still allowed)
Comments
Well all you have to do is change your 4+ diamonds to 5+ diamonds and then you are OK. (You can further restrict a call that otherwise qualifies)
My own opinion is that the bid is too wide ranging to accurately defend: I would also wonder what methods the partnership would have to actually locate the second 4-card (or possibly longer) suit quickly and conveniently - aren't we entering Italian-style double or 'fert' territory?
And is it playable?: Given a 5=2=4=2 hand, won't a player with 3=3=3=4 just pass.
There's been quite a bit of research done on this specific opening. I'm not convinced it's actually good (otherwise I'd probably be playing it myself), but it does at least seem to be playable (and as a pre-empt showing two suits without going beyond the 2 level in either, I'd expect the version that shows only 4-4 to be the best version of it; when you can stop at the 2 level, showing 4-4 definitely seems to be best when you have two known suits or the lower-ranking suit is unknown, which makes it decently likely that it's also best when the higher-ranking suit is unknown).
It does generally tend to be played as exactly 4 cards in the major (but 4+ diamonds), though. (Without that, though, in your hypothetical 5=2=4=2 opposite 3=3=3=4 problem, responder would correct to the major; if the majors are as likely to have length as the diamonds are, then you correct to the major because it's higher-scoring and may make it harder for the opponents to bid the other major.)
The usual follow-ups seem to be 2H as pass or correct for the major, and 2S as natural spades (with pass available to play in 2D); strong hands can use 2NT as a forcing ask (which locates the major, among other things). This does sometimes lead to guesswork when you'd prefer to play in 2D opposite one major but 2M opposite the other, but it isn't relevant that often because it's very common for the opponents to overcall over this sort of opening (saving you from the trouble of working out whether and where you have a fit), and it's more common to want to play diamonds regardless, or play the major regardless, than it is for the choice to differ based on which major partner has.
The call's quite different from a fert because it shows a specific 4-card suit, and is limited to two particular hand types (although both ferts, and pre-empts that show 4-4, tend towards being balanced, there are much fewer possibilities in the latter case). This matters a lot when the opponents try to penalise – there are 10 basic hand types you might want to show after ferting (6 two-suiters and 4 one-suiters, plus 4441s and 4333s but those normally get lumped in with the others), but only 2 after you make a 4D4M pre-empt, so escaping from a penalty double is five times as accurate.
(It's worth noting that I play something pretty similar in later rounds of the bidding – if my partner's weak 1NT gets doubled, I have a way to show clubs + an unspecified major without pushing the bidding above 2C. The ambiguity of the bid hurts in theory, but hasn't so far in practice, because most opponents are unwilling to risk the possibility that we might pass out 2C; and thus although we have a way to ask for the major, we've never yet needed to use it.)
This was part of standard Warwick when I was at university, it can be a lot of fun to play but you do learn to scramble for tricks in dodgy 2 level fits. Not a bad bridge education but probably not an optimal approach. The major is generally exactly 4, since with 5 there's a weak two in a major available. Diamonds is 4 trending towards 5 depending on position & vulnerability & temperament, there's a tendency to pass with D tolerance rather than look for the major.
I've never thought of it as particularly tricky to defend against since you can essentially treat it as a weak two in diamonds. The only tricky system point is when the opponents have a big diamond fit, I'm aware of at least two cases where it kept opps out of 6D
I'm a little bit surprised it's not legal anymore, since as far as I'm aware it's been permitted for 20 years or so and I know a couple of pairs that still use it. As John says, so long as it promises 5!D there's no problems.
Forbidding 2D=4+-4+, D+M was deliberate, and was confirmed at the L&E meeting in October.
Thanks Robin. I can see the new rules were approved in the May minutes but no rationale was given. Can you shed any more light?
Martin has asked "why?" on Bridge Winner and got replies from David Burn (L&EC chair) along the line of too hard to defend against (or markedly harder than defending against two-suiter with 5 in the suit bid)
Underlying this is a changing attitude to Level 4 by a (much changed) L&E committee. Level 4 is very widely used in clubs, much more than it was in 2006 (when the previous version of 7C emerged). Times change, and the old regulations were not seen as fitting the current use of Level 4.