Fourth Suit Forcing

      SAYC is an "approach-forcing" system.  This means that it relies on Responder (to 1-level opening bids) finding largely natural, meaningful bids to sustain the auction for the first two rounds of the bidding. 

      2/1 GF is a "level-forcing" system when Responder's 1st bid is a 2-over-1 (e.g., 1♦:2♣), but is an approach forcing system, if Responder answers with ONE of a suit (e.g., 1♦:1♠). 

      At the other end of the spectrum lies relay systems, where Responder uses artificial, meaningless bids (called "relays") to sustain the auction.  All approach-forcing systems, including SAYC, rely on two fundamental rules of bidding:

      Fourth-Suit Forcing is an extension of the above Rule #1.  Responder's bid of the 4th suit is usually artificial, and does NOT promise length in the bid suit.

1	1
1	2		– This DOESN'T promise Clubs.

      The 4th-Suit Force (2♣ in the above example) forces Opener to bid again, as any new suit would.  Here, opinion divides:

      The standard treatment is that the 4th suit bid is forcing for only ONE round.  MANY people, however, play it as forcing TO GAME.  Discuss this with any new partner.

1	1
1	??

      1NT does not look like an attractive rebid here after 1♦:1♥:1♠.  So what does Responder rebid, if 2♣ is artificial and forcing ?

      The answer depends upon whether you play the 4th-Suit bid as forcing TO GAME.

1 1 1 3

1 1 1 2 any 3

      If you do, you much Jump to 3♣, NON-FORCING, since 2♣ followed by 3♣ would, by definition, be a game force.
      If, however, you play that the 4th-Suit bid is only a ONE round force, you may rebid 2♣ (forcing) and then 3♣ (NOT forcing). 
      Failure to use the 4th suit as a force always limits the Responding hand.  If, over 1♦:1♥:1♠ Responder were to, say, jump in either major, this would be highly invitational, but NOT forcing (as according to the above Rule #2).  To FORCE, Responder would use the 4th Suit and THEN rebid the major. 

1♦ 1♥ 1♠ 3♠  – NOT forcing.

1♦ 1♥ 1♠ 2♣ 2NT 3♠  – FORCING.

      The same limitation holds true, even if Responder subsequently leaps to game.  The direct leap tends to deny slam interest, while the slow approach (via the 4th-suit force) shows slam interest.

1 1 1 3NT  – 13-15 HCPs.

1 1 1 2 2 3NT  – 16-18 HCPs (else 3NT last time).

Remember:

This, of course, is consistent with the Principle of Fast Arrival, which states that with a mediocre hand we tend to bid game quickly, while a slower, more patient route tends to show a better hand.

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