- opening strength (normally 12 HCP or "Rule of 20" depending upon partnership agreement) and
- support of at least four cards in the opening bidder's major suit.
This response is considered to be forcing to game in the suit of the opening bid. If the partnership plays splinter bids, the Jacoby 2NT response also denies a splinter (either no singleton or void, or stronger than the agreed range for a splinter bid).
Opener's Rebids Over a Jacoby 2NT Response
With a balanced hand, opener rebids as follows:
- With 16 or more HCP opener rebids three of the agreed suit.
- With 14-15 HCP, the opener rebids 3NT.
- With fewer than 14 HCP bids four of the agreed suit.
With an unbalanced hand, there are two common methods of continuing rebidding over a Jacoby 2NT response, the choice of which is a matter of agreement between the partners. These methods differ only in the definition of a bid of another suit.
The earlier method uses the following bids.
- With a void in spades or a singleton in any suit, the opening bidder cue bids three of the short suit.
- With a void in hearts, diamonds, or clubs, the opening bidder cue bids four of the void suit. (Note that the opening bidder must cue bid 3♠ rather than 4♠ with a void in the spade suit so a Jacoby 2NT responder who judges that slam is not in the cards can sign off at 4♥.)
The newer method uses the following bids.
- With another good five card suit, the opener bids four of the second suit.
- With a singleton or void in the absence of another good five card suit, the opening bidder cue bids three of the short suit.
Rebids by the Jacoby 2NT Responder
The Jacoby 2NT bidder must assess how the hands fit, and generally will have the following options.
- The Jacoby 2NT bidder may sign off in four of the opener's major (or pass, if the opener has already bid four of the opening major).
- The Jacoby 2NT may use cue bids and/or slam conventions to find the best contract if the bidding suggests a possibility of a slam.
The 2NT bid is used in some systems to show an invitational or better raise (10 point upwards, at least four-card support, forcing to the three level only) rather than a game force. In 2/1 game forcing and Acol, this is used if opponents double and is called the Jordan 2NT convention in the USA; in the UK, it is sometimes called Truscott. Some books and articles, particularly in the UK, call this Jacoby 2NT, but this is technically incorrect.
The Jacoby 2NT was designed for five-card majors. It can also be used in a four-card major system such as Acol, but it may then be useful to change opener's rebids to allow him to specifically show a hand with only a four-card major, typically by using 3NT. Also, the three and four-level new suit rebids may be swapped so that a three-level bid shows a long suit and a four-level bid a shortage (splinter bid).
In some forms of Acol, a 3NT response is used instead of 2NT to show a hand with 13-15 points, four-card support and no side suit shortage (a "pudding raise").
- Manley, Brent, Editor; Horton, Mark, Co-Editor; Greenberg-Yarbro, Tracey, Co-Editor; Rigal, Barry, Co-Editor (2011). The Official Encyclopedia of Bridge (7th ed.). Horn Lake, MS: American Contract Bridge League. p. 293. ISBN 978-0-939460-99-1.
- ACBL "Bidding Toolbox" Article
- ACBL "In Their Own Words" Article by Jim Jacoby
- ACBL "Bidding Toolbox" Article