Bidding and conventions
Jacoby 2NT
When partner opens a major and you hold a good hand with four-card support, the problem is not whether to bid game — it is whether to bid slam. Jacoby 2NT commits to game immediately so the whole three level is free to find out.
The problem it solves
Partner opens 1♠ and you hold 15 points with four spades. You know you are playing at least game in spades. The only real question is whether the two hands fit well enough for twelve tricks.
Without a convention, your options are all bad. Bidding 4♠ is accurate about the fit and ends the auction before it started. Jumping to 3♠ is invitational, which understates you. Bidding a new suit gets you a description of the wrong thing.
Jacoby 2NT sets the strain and the level in one bid, then spends the entire three level on the actual question.
That is the trade: you give up notrump as a natural response, which with four-card support for a major you did not want, and get four rounds of description for it.
What you need to bid it
- Four or more cards in partner's major. Not three.
- 13+ points, enough to force to game.
- No singleton or void in most partnerships' style — with real shortage, a splinter bid describes the hand better.
- You must not be a passed hand. A passed hand cannot hold 12 points, so 2NT reverts to its natural meaning, or to Drury, if you play it.
15 points, four-card support, no shortage. Game is certain; slam depends on partner.
Also 13+ with four spades, but the singleton heart is the most useful fact about it. Splinter with 4♥ instead.
Opener's rebids — the whole point of the convention
This is the schedule most partnerships play. It is not universal, so agree it explicitly.
- Three of a new suit — a singleton or void in that suit. This is the first priority, ahead of showing strength, because shortage opposite wasted honours is what decides most slams.
- 3NT — a strong balanced hand, roughly 15–17, with no shortage anywhere.
- Four of a new suit — a good five-card side suit, usually with extra values.
- Three of the agreed major — extra values, no shortage, slam interest.
- Four of the agreed major — a minimum opening with nothing else to say. This is the signoff, and responder should respect it.
A hand where it works
14 points. A minimum in high cards, but a singleton diamond and 5-4 shape.
15 points, four-card support, three small diamonds.
| West | North | East | South |
|---|---|---|---|
| 1♠ | |||
| Pass | 2NT | Pass | 3♦ |
| Pass | 4NT | Pass | 5♥ |
| Pass | 6♠ | Pass | Pass |
| Pass |
Responder's three small diamonds are exactly what opener's singleton wanted to hear about: nothing wasted, everything else working, twelve tricks there.
Had responder held ♦ K Q x instead, the same 15 points would be worth far less and the auction should stop in game. That distinction is invisible to point count, and it is what the convention exists to expose.
Agree the details before you play it
Partnerships differ on every one of these, and each disagreement is a hand bid to the wrong contract:
- Whether 3NT shows a strong balanced hand or a minimum one. Both are played, and they are opposite.
- Whether three of a new suit shows shortage or a real second suit.
- Whether the convention applies after an opponent's overcall. Most play that it does not.
- Whether responder may hold a singleton.
If you agree only one thing, agree what a new suit at the three level means. It is the most frequent rebid and the most valuable.