Glasnevin Bridge Club

Forcing Sequences
One of the hallmarks of a well developed bidding system is the ability to make bids which will be seen by partner as unambiguously forcing. A number of such bids are lumped together on this page.

Responder’s change of suit
When opener’s partner responds by changing suit, this is a one round force. Therefore there is never a requirement for responder to jump-shift in order to force opener to bid on. A simple shift suffices. In most systems, the jump-shift response is used to show a powerhouse but an alternative, used in this system, is the weak jump-shift used to show a 6 card suit with fewer than 6 points. Where responder is a passed hand and therefore limited, opener
may pass but will generally be reluctant to do so.


If you open a suit, partner changes suit (forcing) and you now bid a third suit of higher rank that the first one,
such that partner will have to go to the 3 level to show preference for the first suit, that is a reverse. Partner who is minded to show preference will often be quite weak and may be loath to go to the 3 level unless he knows you are strong. Therefore, to reverse, you must have 16+. Breaking this rule is one of the most efficient ways of destroying partnership trust! A reverse is always forcing for one round and in a situation where responder’s first bid was at the 2 level e.g. 1H-2C-2S, it is game forcing since opener has 16+ and responder 10+. Note that 1C-1D-1S is not a reverse as partner can show preference for clubs at the 2 level.


Showing preference is, of course, not forcing - indeed it is just the opposite. In some systems, showing jump-preference is forcing but not here. Showing jump-preference is constructive but
not forcing.

Bidding a New Suit at the 3 Level

The introduction of a new suit into the auction, by either partner, at the 3 level is unconditionally game forcing in most standard systems. It applies in this system with the exception of jump shift responses to opener which in this system are weak (and thus alterable) and can be passes.

Fourth Suit Forcing (4SF)

In an unopposed auction, when responder bids the fourth suit at the 2 or higher level, this is 4SF, a purely conventional bid which says nothing about the fourth suit but asks partner to further describe his hand. It is a forcing bid, depending on system, either for one round or to game but in this system it is unconditionally forcing to game. Why use it? The 4SF bidder knows that game values are present but is not certain which game. The most usual (but not the only) situation is that he knows the values are present for 3NT but is worried about the fourth suit. Whatever the 4SF bidder’s motivation is, partner’s duty is to further describe his hand and in the following order of priority;
  1. With a stopper in the fourth suit, bid 3NT.
  2. Lacking that but with secondary support for responder’s first bid suit, bid that suit.
  3. Otherwise, with extra length in his own suit, rebid it.
The first action ends the auction, the others pass the decision back to the 4SF bidder. Occasionally, the 4SF bidder will now bid 3NT in the absence of confirmation of a stopper from opener. This indicates he has a single stop and passes the final decision back to opener who can either risk passing or plough on in his own suit.

  • Note that 1C-1D-1H-1S is not 4SF. If responder wishes to set up a game force in this situation, his second bid must be 2S.
  • If responder is a passed hand, 4SF is off.
  • Any intervention switches 4SF off.

Bids after 1x-3NT or 1x-1y-3NT

In both these situations, the 3NT bid is to play, often based on a long running minor. Any further bidding by the 3NT bidder’s partner is slam-hunting and thus forcing.

Bids after partner reverses in 2NT

All such bid (short of game) are forcing e.g. 1C-1D-2NT-3H

Bids after partner reverses into 1NT
Normal bids can be passed but a jump bid is forcing e.g. 1D-1H-1NT-3S

Jump bids by opener in a new suit
These show rock crushers and are unconditionally game forcing e.g. 1H-2C-3D

Repeat of responder’s suit
This is often weak except where it follows a jump by opener. Thus while 1D-1H-2D-2H is a weak sequence which opener can (probably should!) pass 1D-1H-3D-3H is forcing.

Responders reverse
Everyone knows that a reverse by opener is forcing but many don’t seem to realise that the same applies to responder’s reverse. A responder should not reverse unless strong and such a bid is a one round force e.g. 1D-2C-2H-2S

Index of Conventions
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