| ... | 4NT | ... | 4NT | ||
| 5x | 5NT | ||||
| 5♣ | 0 or 4 aces | 6♣ | 0 or 4 kings | ||
| 5♦ | 1 ace | 6♦ | 1 king | ||
| 5♥ | 2 aces | 6♥ | 2 kings | ||
| 5♠ | 3 aces | 6♠ | 3 kings |
A jump to 5NT (and some 5NT bids when the auction is at the five level) is "Grand Slam Force", asking partner to bid a grand slam with two of the three top trump honors;
| 5NT | 6 of the trump suit | Fewer than two top trump honors (A, K, or Q) |
| 7 of the trump suit | Two of the three top trump honors |
If the Blackwood bidder wishes to sign off the bidding in 5NT (after realizing too many aces are missing), it can be done by bidding an "unplayable" suit, after which responder should bid 5NT, i.e. 1♥-2♦-3♦-4NT-5♦-5♠ - this forces partner to bid 5NT.
Many partnerships prefer Roman Key-Card Blackwood. With Roman Key-Card partner shows Key-Cards rather than aces. The Key-Cards are the four aces and the king of the agreed trump suit. When there is no agreed trump suit it is implicitly assumed that the last bid suit is the trump suit. Roman Key Card Blackwood also identifies possession of the trump queen either directly or with a subsquent asking bid. The responses are as follows:
After one of the first two responses the 'Blackwooder' can make a further asking bid for the trump queen. The trump queen ask is a bid the next step above the response but excluding the trump suit i.e. over 5♣ the ask is 5♦ unless diamonds are trumps when it is 5♥ and over 5♦ the ask is 5♥ unless hearts are trumps when the ask would be 5♠. In response to an ask for the trump queen partner bids the next 'step' to deny the trump queen and the second 'step' to show the trump queen.
Over either response to a queen ask or directly after the first response to Roman Key-Card Blackwood the 'Blackwooder' can bid 5NT to ask for kings. Partner responds in steps. We do not count the trump king which has already been included as a key-card in the first response to RKCB.
There are several variations of Roman Key-Card Blackwood. Two popular variations are RKCB 1430 - easy to remember since this is the score for a small slam in a major - in which the first two responses are swapped. The reason for this is that it is believed that after a one key-card it is more likely that slam is still possible and over the first step response there will be more room to make an ask for the trump queen. The second variation is to show specific kings rather than the number of kings in response to a king ask. Without any kings one returns to the trump suit. An extension of this is to show kings automatically in response to the queen-ask when showing the trump queen. The first step (or alternatively a return to the trump suit) denies the trump queen and then any other bid shows the trump queen and the king in the bid suit. A jump in the trump suit shows the trump queen and denies a side king.
Your partnership must thoroughly discuss any of these variations before playing them as the cost are great (and unnecessary) from a Blackwood misunderstanding.
| 4NT | 5♣ | 0 or 3 Key-Cards |
| 5♦ | 1 or 4 Key-Cards | |
| 5♥ | 2 (or 5) Key-Cards without the trump queen | |
| 5♠ | 2 (or 5) Key-Cards with the trump queen |
After one of the first two responses the 'Blackwooder' can make a further asking bid for the trump queen. The trump queen ask is a bid the next step above the response but excluding the trump suit i.e. over 5♣ the ask is 5♦ unless diamonds are trumps when it is 5♥ and over 5♦ the ask is 5♥ unless hearts are trumps when the ask would be 5♠. In response to an ask for the trump queen partner bids the next 'step' to deny the trump queen and the second 'step' to show the trump queen.
| 4NT | 5♣ | |
| 5♦ | 5♥ | No trump queen |
| 5♠ | Shows the trump queen |
Over either response to a queen ask or directly after the first response to Roman Key-Card Blackwood the 'Blackwooder' can bid 5NT to ask for kings. Partner responds in steps. We do not count the trump king which has already been included as a key-card in the first response to RKCB.
| 5NT | 6♣ | 0 kings |
| 5♦ | 1 king | |
| 5♥ | 2 kings | |
| 5♠ | 3 kings |
There are several variations of Roman Key-Card Blackwood. Two popular variations are RKCB 1430 - easy to remember since this is the score for a small slam in a major - in which the first two responses are swapped. The reason for this is that it is believed that after a one key-card it is more likely that slam is still possible and over the first step response there will be more room to make an ask for the trump queen. The second variation is to show specific kings rather than the number of kings in response to a king ask. Without any kings one returns to the trump suit. An extension of this is to show kings automatically in response to the queen-ask when showing the trump queen. The first step (or alternatively a return to the trump suit) denies the trump queen and then any other bid shows the trump queen and the king in the bid suit. A jump in the trump suit shows the trump queen and denies a side king.
Your partnership must thoroughly discuss any of these variations before playing them as the cost are great (and unnecessary) from a Blackwood misunderstanding.
Here are some general rules for cue bidding to find controls once a trump suit has been agreed on. A cue bid is a non-jump bid in an unbid suit (by your side) past 3 of the agreed trump suit. If the trump suit is a minor suit and there are more than one unbid suits, and the bid is below 3NT, it may not be a cue bid, but rather showing natural suit or a stopper for NT.
Rules for cue bids:
- Bid unbid suits first (by your side), and Aces before voids.
- Plan your cue bids. The cheapest cue bid may not be the
best bid, as it may cause your next cue bid to be higher
than if you reversed the order. I.e., 4♣-4x-4♠ rather than
3♠-4x-5♣.
- Cue aces first, kings second. On occasions, especially if
you are known to be weak, it is necessary to cue a second
round control before first round control in that suit has
been shown or denied.
- Below game, return a cue only if slam appears possible -
with a poor minimum return to the trump suit. If partner cues
again, or cues above game you must return the cue if possible.
- To cue above five of the trump suit is a try for seven.
- If either partner is able to judge the correct final contract
he should bid it as soon as possible.
- If a cue bid is doubled, redouble shows second round control of
that suit, to pass is neutral conveying some interest.
- Avoid cue bidding singleton or voids in a suit bid naturally
bid by your partner.
Italian Cue-Bidding is an alternative cue-bidding style. The main difference with Italian Cue-Bidding is that first and second round controls are treated equally. Here are some rules for Italian Cue-Bidding:
- Cue-Bid your cheapest control - up-the-line. If hearts are agreed then spades is the cheapest cue followed by clubs and then diamonds. A control is any ace, king, singleton or void in the suit bid
- After any number of cue-bids below game either partner ask for key-cards with RKCB
- Unless asking for key-cards after partner has initiated a slam try with a cue-bid or a forcing raise cue-bids below game are mandatory unless it has become apparent that there is a suit that is not controlled - partner has bypassed the suit denying a control and you also have no control in that suit. Consequently a cue-bid in a new suit shows a control in the suit bid and a control in any suit by-passed by partner.
- A cue-bid that commits the partnership to a higher level necessarily shows extra strength
- Do not cue-bid a shortage (singleton or void) in partner's long suit. Occasionally it is possible to make a later cue-bid in partner's suit having already denied a control there to show a shortage
