LEBENSOHL

This convention is used when our side opens 1NT and the next player (opponent) comes into the auction.

Our responder's bid of 2NT is artificial and alertable. It says nothing about notrump. It requests that the 1NT opener bids 3 next (no matter what he has). After that, the responder can pass if he wants to play in 3. If he bids some other suit on the 3-level, that is also to play.  Here are some examples:

S	W	N	E
1NT	2	2NT*	Pass
3	Pass	3

*alertable "puppet" to 3

S	W	N	E
1NT	2	2NT*	Pass
3	Pass	3

 *alertable "puppet" to 3

In both auctions, North is placing the contract. He might have KJ10876 in the suit and no other points.

If he wants to force his partner to bid again, he bids directly as here:

S	W	N	E
1NT	2	3

 What is the purpose of this convention? It is so the partner of the 1NT bidder can make a normal forcing 3-level bid (game forcing, actually), but also have the ability to sign off on the 3-level. He uses the 2NT puppet to 3 to sign off. He bids directly on the 3 level to force.

A new suit on the 2-level is not forcing. So 1NT (2) 2 is to play.

That's the easy part. There are other parts to learn. The responder can use a cue-bid. He can bid the suit which was overcalled. For example:

1NT (2) 3

Not only that, he can cuebid it after using the 2NT puppet:

1NT (2) 2NT Pass
3 (Pass) 3

 

Both of those 3 bids should be used as Stayman. Why have 2 ways to send the same message? I'll answer in a moment.

First, I want you to realize that there are also 2 ways to raise to 3NT! Yes. There is no way any more to play in 2NT (since it is artificial), but the responder can bid 3NT as in 1NT (2) 3NT.  But, he can also bid that 3NT the delayed way as in: 

1NT (2) 2NT Pass
3 (Pass) 3NT

So, if you're with me, there are 2 ways to cuebid and 2 ways to bid 3NT. We use "FADS" to make the distinction. This stands for "Fast Always Denies Stopper." What does "Fast" mean? It means you bid directly--not going through the 2NT puppet. "Slow" (going through 2NT) would show a stopper. The stopper refers to their suit. So, you have 4 things you can do in this arena once they overcall:

1) Raise directly to 3NT to deny a stopper and to show no interest in finding a major-suit fit.

2) Raise slowly to 3NT (via 2NT) to show a stopper in their suit and no interest in finding a major-suit fit.

3) Cuebid directly to deny a stopper but to ask for a 4-card major.

4) Cuebid slowly (via 2NT) to show a stopper and ask for a 4-card major.

So, with:

 AQ43  
 K3  
 765  
 J1065
 , if partner opens 1NT and they overcall 2, you can bid 2NT (forcing 3) and then bid 3 as Stayman (with a heart stopper).  If your K were in diamonds, you would bid 3 directly as Stayman. If you took away the king completely, you would make a negative double.

With:

 AQ2  
 K54  
 Q106  
 7642
, if partner opens 1NT and they overcall 2, you would bid 2NT (forcing 3) and then bid 3NT to say you want to play in 3NT and have their suit stopped. If the K were in diamonds, you would bid a direct 3NT to deny a stopper.

This takes study, practice, and a partner on the same page.

Note: If they overcall 2, you just ignore it (so if you bid 2NT after their 2 overcall, you should treat the auction as if it went 1NT PASS 2NT -- however you play it).

You might consider Larry's recorded webinar on lebensohl found HERE. 

Better than this system is something called Transfer-lebensohl. I recommend that only for experience players with strong memories.