One of the most commonly used treatments in modern bidding is the negative double. The negative double is an extremely broad topic, far beyond the scope of a single article to describe fully, but following are some important points.
In its simplest form, the negative double’s objective is to express values and length in the unbid suits — particularly the unbid major(s) — in a competitive auction. For example:
| West | North | East | South |
| 1♣ | 1♠ | Dbl |
Defining East’s double as penalty is impractical: a “business” double of a one-level overcall occurs too rarely to worry about. It’s much more common to have moderate values and a heart suit after the auction begins in this manner, so most players use the double to show a hand such as:
♠ J 8
♥ Q 9 7 4
♦ Q 8 5 4
♣ K 4 2
or perhaps:
♠ Q 5 3
♥ K J 8 7 4
♦ 9 6
♣ Q 10 5
or even:
♠ A 3
♥ A Q 8 5
♦ K 5 2
♣ J 7 6 3
The negative double is vital because it alerts opener to the possibility of a heart fit. The double can also be used, however, to show spades in an auction such as:
| West | North | East | South |
| 1♦ | 1♥ | Dbl |
Most players in North America use this sequence to show exactly four spades. With five or more spades, East could simply bid 1♠.
How much strength does a negative double promise? It depends. The suggested minimum strength for a negative double that would force partner to bid at the one level is typically 6 points. In the second auction, East could double on as little as:
♠ K J 7 5
♥ 10 3
♦ 9 8 4
♣ Q 9 7 2
(With a good fit for partner’s first suit, some players would do it on even less.)
If the double would force partner to bid at the two level (as in the first auction), 8 points is a good minimum. To force partner to the three level — in an auction such as:
| West | North | East | South |
| 1♠ | 2♥ | Dbl |
— East should have at least 10 high-card points. The higher you force partner to bid, the more you should have.
As opener, partner’s negative double can help you choose your rebid. Say you hold:
♠ A 7
♥ Q J 6 3
♦ 8 7 6
♣ A Q 6 2
After opening 1♣, left-hand opponent overcalls 1♠ and partner doubles (negative). This strongly suggests at least four hearts and appropriate values. If RHO passes, you have an easy 2♥ rebid. (Note that this does not promise extra values; you’re just “raising” partner’s hearts.)
Using the negative double, what would this auction mean?
| RHO | You | LHO | Partner |
| 1♠ | 2♦ | 2♥ |
If you had doubled, the double would have shown exactly four hearts. The 2♥ bid, therefore shows five or more. There is also a strength inference involved. Whereas a two-level negative double could show as few as 8 HCP as described above, a direct two-level bid such as your 2♥ shows at least the same number of number of points required for a two-over-one response in “standard” bidding — 10 HCP. (Note that some players would treat 2♥ as a game force, so their two-level bids would promise even more — an opening hand.) An easy way to remember this is to consider what you need to bid 2♥ if North had not interfered. Most systems require a minimum of 10 points to make a new-suit two-level response.
This is a big help to opener, because it immediately tells him something about your strength and heart length. For example, say you held:
♠ K 7
♥ A 9 4
♦ K Q J 8 2
♣ 10 8 2
You open 1♦, LHO overcalls 1♠ and partner bids 2♥. What do we know about partner’s hand? She has at least five hearts (a negative double would have promised only four) and at least 10 HCP, making the raise to 3♥ a standout.
The negative double lets you tackle problem hands such as this:
♠ K Q 10 9 6 5
♥ J 5
♦ Q 9 8
♣ 5 2
Partner opens 1♥ and RHO overcalls 2♣. You can’t bid 2♠ directly. That would show a good hand — at least 10 HCP. You can, however, make a negative double. If partner bids 2♦, you will bid 2♠. Partner will know that you have a relatively weak hand with a long spade suit, because you doubled first.
Special case
In this auction:
| West | North | East | South |
| 1♣ | 1♦ | Dbl |
East’s double should show both majors. What happens, however, if East is dealt a hand such as:
♠ A J 9 5
♥ Q 8
♦ Q 10 6 2
♣ 9 8 7
In this case, East should bid 1♠. Ordinarily, a direct bid shows a five-card or longer suit, but in this auction (a 1♣ opening and a 1♦ overcall), a 1♥ or 1♠ response may be made on a four-card suit. The negative double should be reserved for a hand with both majors.