Negative double is a very important response tool in the bridge arsenal. It is 100% Forcing and reasons to use this gadget are:

• In uncontested responses, a 4 card Major gets priority over all other bids. However, on a Minor opening by partner when a Major is overcalled, the responder’s 1^st bid becomes a free bid. It means that responder must have 5+ cards of the alternate Major to bid. This deviation in Bridge grammar is handled by a Negative Double, where it indicates 4 cards of the other Major.
• Opening bid of 1 Minor overcalled by 1!s ensures that !h response will be at level 2 and that too, a free bid with 5+ Cards and 10+ points. Negative Double provides alternative bid, a 4+ card !h with 8+ points.
• When opener and overcaller both bid Minors at level 1 i.e. 1!c opening and then 1!d overcall, Negative Double conveys both Majors with 4+ cards in the responder hand.
• When the opener and overcaller bid both Majors at level 1 i.e. 1!h opening and 1!s overcall, Negative Double conveys both Minors with 4+ cards in the responder hand.
• Opening bid of 1 of Major overcalled by 2 level Minor, a Negative double conveys 4 cards in any unbid suit at 8+ points.

Examples :

a. When the opener is able to rebid after your DBL at Level 1. It means you have 6+ points.

West	North	East	South
1!c	1!h	double	Pass
1!s

in the above situation East can double with just 4 cards whereas bidding 1!s will indicate 5 cards in spade suit as it is a free bid.

b. Interference by !s will make !h bidding at level 2 and also a free bid with 5+ cards

West	North	East	South
1!c	1!s	double	Pass

In the above example ordinary course of action will not allow south to bid hearts if he has 8+points and 4 Cards of !h. He will have to bid 2!h that too with 5+ cards and 10+ points. Reason:

• level 2 response will have to be at 10+ points.
• 1 Minor opening overcalled by a Major makes response a free bid which requires 5+ cards of the alternate Major.

But if he bids DOUBLE. The opening partner now knows that south has 4 cards of !h with 8+ points. So his next bid can be appropriately at lower level.

c. When the opener is forced to rebid after your DBL at Level 3. It means you have 10+ points.

d. When the opener is forced to rebid after your DBL at Level 4. It means you have 13+ points.