DUPLICATE BRIDGE: THE JACOBY 2NT CONVENTION.

 JACOBY 2NT RESPONSE TO AN OPENING BID OF 1 HEART OR I SPADE.

When partner opens the bidding with 1 heart or 1 spade and you have:

                  a) A 4-card support
                      and
                  b) 13 or more points

The Jacoby 2NT response is often used to explore the possibilities for slam.
This convention gives up the natural meaning of the 2NT bid but, helps the partnership to explore bidding at the 6 or 7 level instead of the usually 4 hearts or 4 spades.

EXAMPLE:  Partner opens 1 spade with the following hand:

 A K 10 9 8
 K J
 K Q 6 5 4
 Q

You have:      J 7 6 5                     Respond:  2NT (Jacoby)
                      A Q 9 8
                      A
                      K 9 5

With 14 high card points and 3 points for the singleton A of diamond, responder feels comfortable to explore slam with the proper rebid by opener.

Here are the possible rebids by opener after responder bids 2NT (Jacoby).

1.  With a singleton or a void, bid that suit at the three level. 
2.  With a second good 5-card suit, bid that suit at the four level.
3.  With no feature and a minimum hand, jump to game in the original suit.
4.  With medium strength 13 to 15 points, rebid 3NT.
5.  With Maximum strength 17, 18 or more points, rebid the agreed suit at the three level.

EXAMPLES:     Partner opened 1 Heart.  You respond, 2NT
                           With the following hands, opener rebids:

K 9 8                         Rebid 3D
A 10 7 6 5
J
A Q 9 7

3 diamonds is the conventional bid to show a singleton diamond.  This information can prove useful to the responder especially if his hand contains the ace of diamonds.

10 9                          Rebid 4D
A K 10 9 8
A K 9 7 5
2

The 4 diamonds shows a good 5-card diamond suit.  If responder can attack the losers in the other two suits, slam can be a possibility.

10 9                        Rebid 3NT
A Q J 6 5
K Q J 5
Q 10

With the above medium hand of 15 points, opener rebids 3NT, conventional.


9 8 3                       Rebid 4H
A J 10 9 7
K Q 8
K 5

With no feature, no additional 5-card suit and a minimum hand, opener rebids 4H, a closeout bid.

A                            Rebid 3H
K Q J 10 5
K J 5
K 10 5

With a maximum hand, opener rebids 3 of the original suit, conventional.


RECAP:

Jacoby 2NT is to be utilized by the responder when the possibility of slam exists. With an opening hand and no special features, responder can make use of other bids to reach the final contract.

Examples:

1.  Limit raises
2.  Bergen major suit raises
3.  Splinter bids etc.