... and how to deal with interference

When you partner opens 1NT and the opponents intervene, even simple overcalls can mess up your beautifully laid down conventions. Here are some hints on how to deal with such interference:

Lebensohl:
When the intereference is at the 2-level, 2NT can be played as lebensohl. The key ideas are:
- Bidding a suit at the 2 level is natural and weak.
- If you wish to bid a lower ranking suit, you will need to bid at the 3 level. In such a case, bidding 2NT is forcing the 1NT opener to bid 3C, pass or correct. Bidding in this manner shows seven points or less, and no interest in game. Eg. 1NT-2H-2NT-P-3C-P-3D is to play in 3D.
- Bidding a higher ranking suit in such a manner is invitational to game. Eg. 1NT-2H-2NT-P-3C-3S is invitational to game.
- Directly bidding at the 3 level is natural and forcing. Some partnerships prefer to play direct, non-jump overcalls in a minor as constructive and non-forcing.
- Directly cue bidding opponent's suit is stayman and denies a stopper; cue bidding via 2NT-3C shows a stopper.
- Jumping to 3NT shows a minor oriented hand without stoppers in opponent's suit. 1NT bidder is expected to correct to game in a minor of his choice if he does not have stoppers either.
- Bidding 3NT through lebensohl is to play and shows a stopper. Eg. 1NT-2H-2NT-P-3C-P-3NT is to play.
- Double is penalty.

Of course, all this applies for natural overcalls. With artificial overcalls, especially those showing two-suited hands, it is still possible to play lebensohl but you will have to work out a lot of details. It gets complicated, and I'm not going to explain them here.

A longer explanation of lebensohl can be found here: http://www.bridgeguys.com/Conventions/Lebensohl.html

Systems on:
Keeping stayman and transfers enabled on interference is called having "Systems on". If the interference is simply in the form of a double, you lose no bidding space and can bid as usual. If the interference is at the 2 level, you can play transfers on along with lebensohl if you wish.

To keep transfers on, you need to sacrifice the penalty double for the Shadow Double. Here, doubling the opponent's bid means "Hey, I was going to bid that." Eg. 1NT-2C-X is stayman and 1NT-2D-X is transfer to hearts. I personally prefer lebensohl with systems off on all overcalls except for 2C, in which case shadow double and systems on apply. The reason for this is if you need to cue bid via lebensohl for stayman with a stopper, 1NT-2C-2NT-P-3C-P-? leaves you hanging as the 3C relay takes away your bid.

Escaping a doubled no trump contract:
Playing 1NT doubled, vulnerable with a balanced hand and zero points in dummy can be quite a disaster - even more so if you are playing weak no trump! There are several escape sequences that can be followed to enable the 1NT opener to bid a 5-card suit or for finding a 4-4 fit. One that I like is the forcing pass in the sequence 1NT-X-?. A direct redouble shows values and is to play; a pass shows a weak balanced hand and asks the 1NT bidder to bid a 5 card suit if he has one, or redouble, leading to the partnership bidding 4-card suits up the line until they find a 4-4 fit or a 4-3 with good honours. In the sequence 1NT-P-P-X, the opener automatically has a chance to bid a 5 card suit, so a pass by him would lead to the partnership straight away bidding 4 card suits up the line, unless the weaker hand chooses to play in 1NT doubled, of course.

A variation that I found interesting is to bid in the manner of DONT. For example, 1NT-x-P is forcing to redouble, after which 2C shows a two-suited hand with clubs and higher ranking suit, and so on for the other 2-level bids. A direct redouble is also forcing to bid 2C, which is pass or correct to a single suited hand. If you really want to play in 1NT, you pass, forcing opener to redouble, and pass again.

Hope this was useful.
Cheers,
Prashanth.