Checkback Stayman

means either Clubs OR Diamonds
means either Hearts OR Spades
1 - 2 means raise in opener's major

CBS usually shows a 5-card major by responder and can be made with any strength hand. Several variations of CBS exist, requiring discussion by partners. The following is a common version.

The bidding by partners goes

    1 - 1
    1N - 2
where 2 is Checkback Stayman.

Opener's responses are 2 for no 4-card major nor 3-card major support or 2 for 3 card in responder's major or 4 in the unbid major.

1-1-1N-2 is also Checkback. Opener again can show 3-card support for Spades by bidding 2 or a strong Heart suit with 2 or otherwise bid 2.

Responder's rebids after 1 - 1 - 1N - 2:

    After 2 by opener:
    • Pass = weak hand and 5 Diamonds.
        If bidding started 1-1, the only distribution which would make sense would be
        5=3=5=0 and even then, you may end up in a 4-3 Heart fit. You probably wouldn't
        have 4=4=5=0 and bid 1 first.
    • 3 = weak sign-off in Clubs. Presumably, you would be 5-5 in the major and clubs.
    • 2 = sign-off in the major; e.g.: 1-1, 1N-2, 2-2.
    • 2N = artificial; invitational raise of opener's minor. Example:
        1 - 1
        1N - 2
        2 - 2N

Regarding opener's 1N bid:

    Opener's choices after 1 - 1 are
    • Bid a second suit of 4+ cards in length.
    • Rebid his original minor with 5+.
    • Bid 1N with 2 of responder's major and a balanced hand.
    • Raise responder's major with 3 when none of the above bids are available.
      Responder's rebids:
      • Pass with fewer than 6 points, even with just 4.
      • With 4 of the major, bid a new suit, raise opener's minor, or bid notrump.
      • With 5+ of the major:
          Reraise to 2 of the major with 6-9 points
        • Reraise to 3 of the major with 10-11 points
        • Self-splinter with a singleton/void.
          Example:
            1 - 1
            1N - 2 - Checkback
            2 - 3 or 4 = singleton/void, game force.
        Bid game with 12+ points.

Checkback Over 2N:

    The May 4, 2019 "Aces" bridge column (by Bobby Wolff) shows the hand QT97 AK764 2 A72 and the bidding with EW passing:

         N S
        1D1H
        2N3C
        3Hetc.

      where 3 is Checkback Stayman and 3 shows 3 hearts.

CBS is similar to New Minor Forcing except that in NMF, after 1-1-1N responder must bid 2 (new minor) instead of 2 and then without a major suit bid, opener must bid 2N. This robs responder of space to sign off with 2 or with a pass of CBS's 2 response by opener.


For a deeper discussion, see BridgeGuys.com.