The weak no trump

The strong 1NT opening is commonplace throughout US bridge, at all levels of competition, and regardless of system. However, for the average player, using a 12-14 opening NT presents no problems, and is generally a significantly better choice both in terms of causing problems for the opposition and in terms of simplifying the constructive bidding challenge. There are some differences of approach that you must adopt, if you are switching to a weak NT for the first time, and there are certain dangers that you must pay attention to. But if you are afraid of being doubled for a large penalty, rest assured that this rarely happens if you take reasonable precautions.

Generally speaking, the same systems of responses that you use with a strong NT will work just as well (or better) with a weak NT. Opener is about a king weaker than you are used to, so to take forward-going action, responder must be about a king stronger than you are used to. As a rule of thumb, responder should not be considering game unless he has at least 11 hcp. Most hands in the 6-10 point range will be passing, or seeking to settle on a suit part-score if that seems preferable to 1NT. With about 11 hcp, responder can consider his hand invitational, and with 12+ he should drive to game. This may seem a little aggressive, since I am suggesting that a balanced 12 opposite 12 constitutes material for game. But it is a fact that the hands generally play better when the strength is split. If you review some of your results, I’m sure you will find that 12/12 was easier to play, and more successful, than (for example) hands where the split was 15/9 or 18/6.

With less than about 6 points, responder should consider taking evasive action even before anyone starts doubling. It is a fact that many opponents who would double 1NT in a flash are much less certain when faced with a Stayman or transfer sequence. And rightly so, I should add, since the vagaries of distribution may nullify some of their high-card strength. And of course, if the auction should start 1NT – double, responder needs to be able to escape to a suit part-score when that seems advisable.

A fairly basic responding scheme that I would suggest would be based around 4-suit transfers. That's an old idea that is familiar to many (most?) people, and it still works pretty well. For example:
2♣ - Stayman
2♦ - transfer to ♥
2♥ - transfer to ♠
2♠ - transfer to ♣
2NT – transfer to ♦
3♣ - 5-5 in the minors, weakly invitational
3♦ - 5-5 in the minors, game forcing
3♥ - 5-5 in the majors, invitational
3♠ - 5-5 in the majors, game forcing
3NT – to play
4♣ - Gerber
4♦, 4♥ - Texas transfers to 4♥, 4♠ respectively
4NT – quantitative, inviting 6NT
5♣, 5♦ - to play
5NT - quantitative, forcing to 6NT, inviting 7NT

I'll expand (expound?) on some sequences in a later post.

Why do I say that the weak NT helps constructive bidding? Well, the argument revolves around balanced hands in the 12-17 range. Some of these hands you will open 1NT. Some you will open 1m and rebid 1NT, and the opened suit may be less than stellar. Playing a strong NT, I have had sessions where I seemed to be opening 1♣ on 10xx all evening. If you play a weak NT, this doesn't happen so often, for the simple reason that 12-14 point hands are much more common than 15-17 point hands. And the dynamics of the auctions for the 12-14 point hands is completely different. If you open 12-14 point hands 1m, the opponents don't know that you are weak, and you and your partner have scope to find a playable spot at the 1 or 2 level if he is weak also. The result is that you are safe from penalty doubles, except for really pathological distributions. But also, the opponents have plenty of scope to get involved in the auction, and since the opener is unlimited, responder may feel the need to get involved on fairly poor values while having little idea of either your strength or distribution. If you open these hands 1NT, you get the hand off your chest at once. Responder knows immediately whether you are looking at part-score, game or slam, or if the hand really belongs to the opponents. The response system means that you can identify suit fits as necessary and proceed with well-defined stop/invite/force sequences. The opponents meanwhile have been robbed of a whole bidding level, and while much is made of the possibility of them doubling for penalty, you shouldn't overlook the prospects of you doubling them. If they intervene at the 2 or 3 level and responder has 8-10 points and suitable distribution they may find they have “stepped in it”. And when you do open 1m, responder knows that either you have a real suit or you have 15+ points. Either case will make competitive auctions more tractable.