"Double" is the most versatile bid in bridge. It is used to disrupt the bidding, to encourage a response from a partner, or to generate much higher penalty points if the opposition does not make their bid.
Even though doubles are common bids, I suggest players who are learning to bid should ignore the "double" for now, and focus on learning the basic concepts of bidding. The player has to know what the normal response would be without an intervening double, in order to know how to alter that bid (or not) after an intervening double.
Like all bids except PASS, the meaning of the bid "double" is determined by the circumstances at the time it is used. The meaning, use and reasons for using the double are varied. This makes learing the double somewhat difficult and confusing. As the novice player gains more experience, the meaning, use and reasons for the double will slowly make more sense.
The double can only be used after the bidding has been started. The double does not have a hierarchy, and does not effect the hierarchy of other bids.
The following are various types and meanings of the "double":
Other Doubles: (not discussed in this website)
• Optional Double
• Responsive Double
• Support Double
• Maximal Double
• Lightner Double
• Card-Showing Double
• “Do Something Intelligent” Double
Penalty Double (SAYC) This is the most widely known double. The penalty double is never used at the early stages of bidding. It is ony used toward the end of the bidding process. This bid means “I doubt you will make that contract, and I will get a higher amount of undertrick points if you do not make your contract”. The bidding process remains open for the other 3 players. The doubler’s partner is not expected to respond.
Takeout Double (SAYC) The takeout double is generally used immediately after an opponent makes the opening bid. It does not imply a penalty against the opener, but a desire for a response from the doubler’s partner. The take out double is used when an overcall is not a more appropriate bid. The conditions for a take out double are:
• When the doubler has a legitimate opening bid that would be make if the opponent did not make an opening bid.
• If the doubler has a legitimate bid in another suit:
• there is no concern for the opener's suit - doubler can stop the opener’s suit with a very short opener’s suit (doubleton, singleton or void) with a high, protected honor in the opener’s suit
• there is reasonable support or stoppers in the other 3 suits.
• If the doubler has a legitimate bid in the same suit, there must be a second 5-card suit, or a strong 4-card suit (with 4+HCPS in that 4-card suit).
The doubler’s partner is expected to make a bid, even without regard to normal response criteria. The response keeps the bidding open so the doubler can make another bid. However, if there is an intervening bid, the doubler’s partner is not obligated to make a response.
Negative Double (SAYC) A negative double is made when the partner (seat 1) makes an opening bid of 1 suit and the RHO (seat 2) makes an overcall. The doubler (seat 3) promises at least 2 of the un-bid suits to play, or the unbid major suit and the opener's minor. The doubler's point requirements are:
• 6+ points if the RHO overcalls at the 1-level (SAYC)
• 8+ points if the RHO overcalls at the 2-level (SAYC)
• 10+ points if the RHO overcalls at the 3-level (not part of SAYC, but it is common and by partnership agreement)
• There is no upper limit on points for the negative doubler.
Reopening Double This is not part of SAYC, but is a widely used practice. When a player (seat 1) makes an opening 1-level bid which is followed immediately by an overcall (from seat 2) and a PASS by the partner (seat 3) and seat 4, the opener doubles to "re-open" the original opened suit.
Lead-Directing Double This is not part of SAYC, but is a widely used practice. The double does not indicate a penalty situation nor a desire for an immediate response, but is often used after an artificial bid (including Gerber and Blackwood). The doubler realizes the opposition is going to win the copntract, so the double tells the doubler’s partner which suit to lead.
"You Stole My Bid" Double This is not part of SAYC, but is a widely used practice. When an opposing player on the right (RHO) makes a bid that the player wanted to make, the player bids "double" to indicate to the partner that the "RHO stole my bid" !