Transfer Lebensohl / Rubensohl / Jordan Style

Okay, so we started with 1NT, and the opponents have interfered at the 2 level. (It is optional whether you want to use this system over 2♣).

The basic idea is that we use transfers into 3 level suits, which gives the minor advantage of having the right hand declare, and the bigger advantage of letting us know what our suit is. If Advancer competes, Opener will have some idea whether we have a fit worth competing in, or whether to prefer defense.

NYC Standard is "slow shows, fast denies", but this system is generally backwards of that: fast bids tend to show stoppers.

Responder's First Bid

2 level bids are all to play.
2NT through 3♥ (ALERT) are all transfers to the next higher suit.
3♠ALERT is a "stopperless responsive double". In the specific case where the opponents have bid 2♦, it shows 5♠+4♥ (added 2024-04-03)
3NT is to play, promising a stopper

After a Transfer to Our Suit

Like lebensohl, there are two cases based on whether the target suit was biddable at the 2 level. If 2X was available, then the transfer promises at least invitational strength with 5+ X, and Opener accepts the transfer only with a minimum. If 2X was not available, then the transfer may be only "competitive" and Opener is expected to accept. Opener may, of course, use judgement to super-accept with a suitably good hand.

After Opener Accepts the Transfer

Responder can now clarify which sort of they had hand:

Pass - simply competitive
New Suit - shows 5-4 in the two suits with a game force; typically without a stopper.
Cue Bid - "forcing". Could be uncertainty about strain or could be (mild) slam interest.
3NT - to play; if the transfer suit was a minor, this typically denies a stopper (letting us bail to 4m when appropriate). If the transfer suit was a major, this is ambiguous about the stopper situation.

After a Transfer to Their Suit

This scenario is "Stopper Ambiguous Stayman", promising at least one 4 card major (which is not the opponents' suit!). Note that if the Opponent's bid is ambiguous (e.g. 2♦ multi) then Responder's 3♣ just shows diamonds, and is not a cue bid. So Responder without a 5 card suit to show should start with Double and proceed from there.

Opener's Responses are:

Accept the Transfer - denies a stopper, missing at least one relevant major.
3M - exactly one 4 card major, shows a stopper
3NT - no (relevant) 4 card major, shows a stopper.
4♣ - both majors (when possible), may or may not have a stopper. Now Responder can:
- 4♦ - transfer to 4♥
- 4♥ - transfer to 4♠
4X - has a fit for the only relevant major; if X<M then this is a control bid showing slam suitability. Says nothing about stoppers

In all cases, further bidding proceeds naturally. Note that once Opener has denied a stopper, Opener still bids 3NT with nothing else to say and it is up to Responder to pull if there is no stopper.

I tried to make the above generic, but things do change based on which suit the Opponents have shown. Going into a bit more detail:

Over 2♦

After 1NT-(2♦)-3♣-(P),

3♦ALERT - no stopper, 0 or 1 majors.
3♥ - stopper, 4 hearts, 3- spades. Responder bids naturally
3♠ - stopper, 4 spades, 3- hearts. Responder bids naturally
3NT - stopper, no major. Responder bids naturally
4♣ALERT - both majors

Also, 1NT-(2♦)-3♠ shows 5♠+4♥. The other way around you can trasnfer to hearts (3♦) and bid 3♠<

Over 2♥

After 1NT-(2♥)-3♦-(P),

3♥ALERT - no stopper, 3- spades
3♠ - stopper, 4 spades
3NT - stopper, 3- spades
4♣,4♦,4♥ - excellent hand with 4 spades
4♠ - no stopper, 4 spades

Over 2♠

After 1NT-(2♠)-3♥-(P),

3♠ALERT - no stopper, 3- hearts
3NT - stopper, 3- hearts
4♣,4♦ - excellent hand with 4 hearts
4♥ - 4 hearts (stopper ambiguous)

After 3♠ "Stopperless Responsive Double"

Like a regular Responsive Double, if the Opponents have bid a minor, this shows both majors. If the Opponents have bid a major, this shows both minors. Opener may bid 3NT with a stopper or make the best guess at the 4 level.

When Opponents Show Both Majors

(This includes 2♣) Broadly the system looks very similar. Responder can bid:

2M - inv or better, shows a stopper in M and denies one in OM. Over which Opener can:
- 2NT - either OM unstopped or minimum
- 3m - either OM unstopped or minimum, 5 card suit
- 3OM - max hand, half-stopper in OM
- 3NT - max hand, stopper in OM
2NTALERT, 3♣ALERT - transfer to minor. After which 3M is forcing to 3NT/4m and shows a stopper in M. 3NT would be forcing to 3NT/4m implying no stoppers. In retrospect, it seems more intuitive for the cue bid to deny a stopper and 3NT to show one
3♦ALERT, 3♥ALERT - transfer to major. Implies M is a viable strain to play despite the known bad break.
3♠ALERT - both minors, no stopper, forcing to 3NT/4m
3NT - stoppers in both majors