All doubles below game are negative, unless there is a conventional
situation which has been specifically discussed. In particular one
cannot double for business if partner has not promised any values. Here
are a few business double situations (usually after partner has made a
negative double):
Who: The advancer
When: Immediately after opponent intervention
Meaning: No other possible bid
Level: 4D
Who: The opener
When: After advancer bid a major and RHO intervened (not in NT) or raised his partner’s suit
Meaning: Usually 3-cards in partner’s suit. May also be any very strong hand that cannot make another bid
Level: 2S – beyond and up to 4D it is strictly for extra strength
Who: The defensive bidders
When: As a response to partner’s Takeout DBL when opponents raise a suit
Meaning: Similarly to the Negative DBL – when there is no other bid available
Level: 4D
Who: The defensive bidders
When: As a response to partner’s Over-call when opponents raise a suit
Meaning: Similarly to the Negative DBL – when there is no other bid available
Level: 4D
Who: The opener and the advancer
When: Opponents over-call and raise a suit
Meaning: Similarly to the Negative DBL – when there is no other bid available
Level: 4D
Who: Anyone
When: Strictly speaking, the Competitive and Responsive doubles belong to the same family.
Meaning: No other bid available, but does not want to let opponents play at their current spot.
Level: 4D
Who: Opener or Over-caller
When: Opponents bid and partner passes or bids 1NT
Meaning: A much-better-than-promised-so-far hand.
Level: 4D
Who: Anyone
When: Partnership has bid and raised a suit and – due to competition – there is no space for another game trial bid.
Meaning: Invitation to game.
Level: 3H
Who: The partner of the over-caller (4th seat)
When: 3 different suits have been bid without jumps
Meaning: A good 4th suit with a tolerance for partner’s suit. By inference the bid of the 4th suit denies tolerance.
Level: 2S