Bidding and conventions
Blackwood, and Roman Key Card
Blackwood is a 4NT bid that asks partner how many aces they hold, so that a partnership about to bid slam can check it isn't missing two of them. This page covers the responses, Roman Key Card, Gerber, and the hands where the ask doesn't help.
What it's for
Don't use Blackwood to find out whether to bid a slam.
By the time you bid 4NT you should already have decided that twelve tricks are there, provided you aren't missing two cashable aces.
Its job is to stop you bidding a slam off the top two tricks. Settle whether the hands fit, whether the suits break and whether the tricks are there before you ask, because the answer tells you nothing about any of that.
| West | North | East | South |
|---|---|---|---|
| 1♠ | |||
| Pass | 3♠ | Pass | 4NT |
| Pass | 5♥ | Pass | 6♠ |
| Pass | Pass | Pass |
When not to ask
Blackwood goes wrong when you ask on a hand where the answer can't help. Four cases:
- You have a void. Blackwood counts aces and a void is as good as one, but you can't tell partner about it. You might also be counting an ace opposite your own void, which takes no trick at all. Cue-bid instead.
- You have two quick losers in an unbid suit. Partner can hold two aces and you can still be off ♣ A K, and Blackwood won't tell you.
- No trump suit is agreed. Then 4NT is almost certainly quantitative (see below), and partner will pass it.
- You can't stand the answer. If a reply of one ace leaves you at the five level in a contract you didn't want, don't ask. Bidding 4NT commits you to at least the five level whatever comes back.
Roman Key Card Blackwood
Ordinary Blackwood leaves out two important cards. The king of trumps is worth about as much as an ace, the queen of trumps often decides a slam, and neither is mentioned.
Roman Key Card covers both. It counts five key cards (the four aces plus the trump king) and folds the trump queen into the answer.
The common version is called 1430, after its first two responses:
- 5♣: 1 or 4 key cards.
- 5♦: 0 or 3 key cards.
- 5♥: 2 or 5, without the trump queen.
- 5♠: 2 or 5, with the trump queen.
The paired answers (1 or 4, 0 or 3) are rarely ambiguous: the asker has enough information to know which, because a partner who could hold four key cards would have done something other than raise quietly.
The other version, 0314, swaps the first two responses so 5♣ is 0 or 3. Both are widely played.
Agree which one you play. Two players on different versions will misread each other's answers and can bid a slam missing an ace.
After the answer
- 5NT: asks for kings, and by bidding it you've promised the partnership holds all the key cards. It's a grand slam try, so only bid it when a grand slam is possible.
- The cheapest bid that is not the trump suit: the queen ask, when the answer didn't settle it. Responder returns to the trump suit without the queen and bids something else with it.
- Five of the trump suit: the signoff, when the partnership is missing too much. Before you ask, make sure you're happy to play there.
Gerber: the same question over notrump
4♣ asks for aces, and it is used only directly over a natural notrump bid. Everywhere else 4♣ is needed as a natural bid or a cue.
- 4♦ = 0 or 4 aces
- 4♥ = 1
- 4♠ = 2
- 4NT = 3
It exists because the ace-ask has to stay below game. Asking at 4♣ leaves room to stop in 4NT; asking at 4NT doesn't.
The usual rule is "Gerber only over notrump". It goes wrong when one player bids 4♣ over a suit as Gerber and partner reads it as clubs.
Cue-bidding instead
Experienced partnerships often use cue-bidding before Blackwood, or in place of it. Once trumps are agreed and the partnership is past game, a new suit shows a control there: an ace or void first time round, a king or singleton later.
The two hands then trade information about where their strength is, as well as how much of it there is.
Cue-bidding locates the losers and handles voids, which Blackwood can't. Blackwood is the last step, once only the ace question remains.