At its basics, a negative double is a double by you when your partner has opened the bidding with a minor suit (clubs or diamonds), and your Right Hand Opponent (RHO) has overcalled a major (hearts or spades). Your double tells your Partner that you have exactly four cards in the unbid major and a certain number of High Card Points (HCP). It also implies support in the other unbid suit, but this is not an absolute requirement.
One level negative doubles
Let's say you're in third seat and the bidding has gone 1 Diamond by your partner, 1 Heart by your RHO and you hold the following:
Not wonderful, is it? But you do have four Spades and you do have six HCP. If your RHO had passed, you would just bid 1 Spade and let it go at that. But how does your partner know how many Spades you have? You could have five Spades, or you could have four Spades.
When your RHO overcalls in this situation, the Negative Double takes care of that problem for you. If you have at least five Spades and this hand, you bid 1 Spade. But if you have this hand, with four Spades, you Double!
This is a conventional bid that doesn't mean what it says. It is not a penalty double. You aren't saying to your partner, "Hey, pard, we got 'em. We can set this baby, so I'm doubling!"
No, it doesn't say that at all. Instead, it says, "Partner, I have at least six HCP and exactly four Spades in my hand. Not five Spades. Not six Spades. Not three Spades. Exactly four Spades."
The requirements for a one level negative double, that is, a negative double that allows your partner to make a bid and stay at the one level, are as follows:
1) At least six HCP;
2) Exactly four cards in the unbid major;
Two level Negative Doubles
The requirements become more stringent as you force your partner to higher levels of bidding. So, look at the following hand:
Bidding goes like this:
P RHO You
1♦ 1♠ ?
Now, you know you can't bid a new suit at the two level without at least ten HCP. If you were to bid a new suit with this hand at the two level you would be lying to your partner. And you don't want to have one of those conversations when she takes action on your promised strength only to find out you lied.
So what are you to do? Your hand isn't bad and you do have four Hearts, which your partner might like to know about. What to do?
Ah, you're probably way ahead of me. Negative double! In this hand you have four Hearts and eight HCP, exactly what you need to make a negative double which forces your partner to bid at the two level. The Negative Double is a terrific way to tell your partner what you have without lying to her.
You might have more than six HCP when you make a negative double at the one level and more than eight HCP when you make it at the two level, but you are promising that you have at least six HCP at the one level and at least eight HCP at the two level.
Again, I am going to stress that you cannot lie to your partner. If, instead of the hand above you had the following:
and the bidding went as above, 1 Diamond by Partner and 1 Spade by your RHO, you may not make a negative double because, if you did, you would be forcing your partner to bid at the two level and you do not have eight HCP. Your bid here would be to Pass. Partner has another bid so you have no obligation to keep the bidding open. You can't bid a new suit at the two level because you don't have ten HCP and you can't bid 1 No Trump because you don't have Spades, your RHO's bid, stopped. So all you can do is pass.
I know a lot of players who would be tempted to make a negative double with this hand, even though they don't have enough HCP. But I hope you are not one of these. Don't lie to your partner.
Following is a chart showing point requirements for negative doubles:
1) If your negative double will allow your partner to bid your suit at the one level, you can make a negative double with only 6 HCP in your hand.
2) If your negative double will force your partner to bid your suit at the two level, you must have at least eight HCP in your hand.
3) If your negative double will force your partner to bid your suit at the three level, you must have at least ten HCP in your hand.
That's a start. We'll get into more variations next time.