Due to (constant) student request, I have given in and written about this annoyingly tricky topic.
How hard can it be? "Just tell us Larry, which bids are forcing and which are not."
It is very hard. It requires study, memory and sometimes partnership agreement (PA).
In this series, it is important to recognize the difference between Forcing (F) and Game Forcing (GF). "Forcing" (F) means your partner "cannot" pass the bid. If he does pass, he does so at his own peril. I might do it once a decade. Suppose my partner opens and I dredge up a response with a very weak shapely hand. He makes a forcing rebid but I bail out with a pass. I'd better be right! "Game Forcing" (GF) means neither partner can pass below game.
In this 5-part series, I plan to break it down as follows:
In this article, we address #3:
3) After Overcalls (by us or the opponents)
If we open the bidding and there is an overcall, a new suit by responder is forcing (but not to game).
The response can be made with only 4 cards if it is 1 or 1 after a 1 overcall (because a negative double would promise both majors). So, 1 (1) 1-MAJOR shows 4+ cards and 6+ points (forcing). But, 1 (1) 1 shows 5+ spades (because a negative double would be made with only 4) and 6+ points (forcing).
In all cases, responder's new suit (after an overcall) is forcing one round (regardless of whether it shows 4 or 5+ cards). This alone can be confusing. If you are struggling, be sure to review negative doubles.
If the response is on the two level, then it shows 5+cards in the suit (and 10+ points). Again, the response is F, but not GF. Example:
2 shows 5 or more diamonds and 10 or more points.
Responder's jump raise (after an overcall) is not forcing--some partnerships play it as preemptive, others as invitational. Example: 1 (1) 3.
What if our responder jumps to a new suit after their overcall, such as 1 (1) 2? That is PA. Some play it as weak, some as strong and others as fit-showing. A double-jump such as 1 (1) 4 should still be a splinter bid.
If their overcall is on the 2-level, our responder's new 2-level suits are forcing (5+ cards) but not GF. If our responder has to bid on the 3+ level, that should be not only F, but GF. Example: 1 (2) 3.
What if they overcall after we have made a response? For example, the auction begins:
North must reverse or cuebid to force. So 2 would be forcing as would 3 (though it is unclear what it means). A rebid in diamonds or spades would not be forcing. The partnership might be using Support Doubles in this situation.
If the opponent jump overcalls and opener rebids his suit on the 3-level, he has a good hand, but his bid isn't forcing. If he bids a new suit on the 3-level it should be forcing.
If we overcall, the partnership has to agree if a new suit is forcing. Possible agreements (choose one):
1) A new suit by the partner of the overcaller is always forcing.
2) A new suit by the partner of the overcaller is always forcing unless one of us is a passed hand.
3) A new suit is forcing if the overcall is on the 2+ level.
4) A new suit is forcing if it is a change of level.
There is no universal way to play this. The partnership also must know if a cuebid promises support. For example, (1) 1 (Pass) 2 = ??
One universal treatment (everyone should play this way) is that a new suit is forcing after we have overcalled their preempt. For example: (2) 2 (Pass) 3 is forcing.
In the next article, we explore auctions with doubles.
Is the last bid in the auction shown F or NF? The reasons for the answer can be found by studying the article ("PA" = Partnership Agreement).
1)F 2)F 3) PA 4)NF 5) NF 6) F 7) PA 8) F