Slam Bidding


Blackwood is one of the oldest conventions, and has now been supplanted by the Roman Keycard version. The same cautions discussed below for RKC also apply to plain Blackwood. It is a tool for avoiding bad slams, not for finding slams.

A bid of 4N, when it is not quantitative, asks how many Aces partner has. The responses are 5♣ for none or 4, 5♦ for one, 5♥ for two, 5♠ for three. Following this, if our side has all four Aces, a bid of 5N asks how many Kings partner has, using the same scheme.

For example:

1♠ - 2♥
3♥ - 4N (Blackwood)
5♥(2 aces) - 6♥ (missing an Ace, stop at six)

Roman Keycard Blackwood (RKC)

In a suit auction, 4N is almost always Roman Keycard Blackwood, which has largely supplanted plain Blackwood. If you are a beginner you can play basic Blackwood but you should learn RKC early on.

The responses are based on their being five keycards, which are the four Aces and the King of trump. If trump has not been agreed to, 4N implicitly agrees (at least for the purposes of responding) to the last bid suit. So, for example, 1♥ – 1♠ – 4N is RKC for spades. The bidder in some circumstances may be intending to end up in some other (higher) suit or notrump but for now responder answers as if the last bid suit is trump, which it very likely is.

Responses (1430) are:

  • 5♣ One keycard or four keycards

  • 5♦ Zero keycards or three keycards

  • 5♥ Two or five keycards but no trump Queen

  • 5♠ Two or five keycards and the trump Queen.

    This can also be bid with two or five keycards and enough trump to guarantee a 10 card fit, even if you do not have the Queen.

  • 5N Shows zero or two keycards and a useful void.

  • 6 of any suit below the trump suit shows 1 or 3 keycards with a useful void in the bid suit.

  • 6 of the trump suit shows 1 or 3 controls and a useful void in a higher suit.

A void is not useful in a suit your partner bid.

The bids shown are the “1430” response. Switch the meanings of 5♣ and 5♦ and it is the “0314” response. Both schemes have their merits but 1430 allows the important “Queen ask” more often when it might matter.

When 4N is NOT Ace-Asking

A bid of 4N is not always RKC or Blackwood. Here are the exceptions:

  • A direct jump to 4N over 1N or 2N, or after a 2N rebid following a 2♣ opener, is quantitative..
  • After a 1N opener and transfer to a major, 4N is quantitative.
  • After a 1x opener, a direct 4N is plain Blackwood. Responder has a self-sufficient trump suit and just needs to ask for aces.

Many pairs play various conventions in which RKC is invoked with some other bid. Most notably, some pairs agree that after an opening of 1m – 2m!(strong), a later jump by either partner to 4m is RKC for m. (Minorwood)

When Not To Bid RKC

It is generally useless to bid RKC if you are missing two keycards and have a worthless doubleton (less than Kx or Ax). The problem is that you learn nothing if partner replies, “One keycard”. You may or may not have two fast losers. In general it is necessary to think ahead and make sure you can take yes for an answer. Learning partner has two keycards but you don’t want to be in a club slam is an unpleasant experience.

When hearts are trump, if partner has two keycards and the trump queen, he will bid 5♠; will you be too high?

When diamonds are trump, if partner has two keys and that isn’t enough, you’re in trouble.

When clubs are trump, playing 1430, if you aren’t going to be able to say yes to zero or three keys, do not bid RKC.

When clubs are trump, playing 0314, if you aren’t going to be able to say yes to one key, do not bid RKC.

The purpose of RKC is to keep you out of bad slams, not to find chancy ones. Use control-bidding to find a custom-fit slam.

What To Do After A 14 or 03 Response

After your partner answers 14 or 03, and if you need it to be the higher number, bid five of trumps. If your partner has 4 or 3 respectively, they bid the slam.

The Queen Ask

If the next suit above the RKC response is below trumps, it is possible to bid that suit to ask for the trump Queen. Responder bids 5 of the trump suit to deny the trump queen, or else bids six of an outside suit below trumps in which he has a King, or 5N to show no outside King below trumps. Bidding six of trumps shows an outside King in a suit above trumps.

Asking For Kings

Asking for Kings promises that the partners hold all five keycards. To ask for Kings, the RKC bidder bids 5N. Responder bids the number of Kings not counting the trump King, using 6♣ is none, 6♦ is 1, and so on.

An alternate by agreement, called “Specific Kings”, is to show your lowest King by bidding that suit if it is below trump. If it is impossible to show a king because it is above 6 of your trump suit. you should either make an impossible bid (e.g., show a king you have denied earlier in the auction) or just bid 6 of your suit.

Responder has the right to just bid the grand slam if he can tell he has “the right stuff”.

Both the Queen Ask and the King Ask responses have variations so make sure you and your partner agree, or just stick to the basics or ordinary Blackwood.

Dealing With Interference

Rarely, your Ace-asking bid may be interfered with. If the opponents overcall 4N in a suit, you can use a convention called DOPI, which stands for “double zero, pass one”. That allows you to give these more negative bids cheaply. In both cases the first available suit becomes your corresponding next higher-level response. It is easiest to be consistent. For example, playing RKC 1430, with diamonds as trump, after 4N - (5♥),

  • Double is one or 4 keycards;
  • Pass is zero or 3 keycards;
  • 5♠ is two keycards, no Q♦;
  • 4N is two keycards with the Q♦, or a known 10 diamonds.

Similarly, after a 4N - (X), ROPI stands for “redouble zero, pass one”.

Note that when the opponent doubles your response to an Ace-asking bid, such as 4N - (pass) - 5♦ - (X), this is normally lead-directing, not penalty, because it is a double of an artificial bid.


When no suit has been agreed upon, we have bid notrump, and at least one partner has not limited his hand, 4♣ is the Gerber Convention, asking for Aces. This is true even if the bidder has bid clubs. The replies are:

  • 4♦ No Aces or Four Aces
  • 4♥ One Ace
  • 4♠ Two Aces
  • 4N Three Aces


Playing with strangers, know that the standard is that 4♣ is Gerber only when it is a jump over 1N or 2N.

Another good test for “Is that Gerber?” is to ask if 4N is Blackwood / RKC. If it is not, then 4♣ is Gerber. If it is, 4♣ is not Gerber. There is no point to having two bids that mean almost the same thing.

After a 1N opener is transferred to a major and responder bids 4N it is quantitative.

Control Bidding

Control bids are slam tries, bid for the purpose of understanding where the partnership may have issues preventing a slam or RKC bid. For purposes of this discussion, we assume that a major suit has been agreed trump in a game-forcing auction. While control bids can be used with minors and with Two Over One, you will have to agree on what three-level bids show controls. In a minor one is more often looking for 3N.

A control bid, formerly called a cue bid when referring to slam tries, is a bid that shows the ability to prevent two fast losers in a suit, such as holding an Ace or a void. Most control bids are at the four level or higher. Control-bids are not jump bids. That piece of knowledge helps you avoid confusing splinters and control-bids.

  • Aces and voids are called first-round controls.
  • Kings and singletons are second-round controls.

The standard method of bidding controls is to only bid first round controls, unless we are already known to possess a first round control in that suit, in which case bidding the suit shows a second round control. (See “Italian Control Bidding” in the next session for a more sophisticated alternative).

  • The first control bid in a side suit shows a first round control (Ace or void) in the suit bid, and denies a control in any bypassed suit. Controls are bid up the line, in other words.
  • If your partner skips over a suit or suits, continuing to control-bid promises a control in the skipped suit(s).

Nothing stops you from cue bidding below the game level and then asking for Aces. For example, 1♥ - 3♥ - 4♦ - 4N. Here, the 4♦ bid showed a first-round control in diamonds and denied holding one in clubs. 4N is RKC, but the bidder is aware of the possible issue in clubs. Instead of 4N, a bid of 5♣ would show that control and deny one in spades. Indeed, suppose responder had xx in diamonds. Normally he could not bid 4N – but knowing diamonds are not going to produce two fast losers, 4N may become possible.

Italian Control Bidding

In the Italian style, a control bid shows a first- or second-round control. A second-round control can be shown without a first-control having been shown in that suit. These rules are applied to interpret the bids:

  • A control bid is a slam try after trump agreement in a major. It promises first- or second-round control. (Again, over minors or in 2/1 these bids are possible but agreement is needed.)
  • A control bid is a non-jump bid in a game-forcing auction with an agreed trump suit. Thus 1♠ - 2♠ - 3♦ is not a control bid because we are not yet in a game forcing auction. But 1♦ - 1♥ - 3♥ - 3♠! is a control bid because bidding on is game forcing and we have suit agreement.
  • A control bid that skips a suit(s) denies a control in that suit. So 1♦ - 1♥ - 3♥ - 4♣ shows a club control and denies a spade control.
  • As long as slam is possible, always show a control bid below the game level. Likewise, don’t control bid if partner has a limited hand and slam is not possible.
  • A control bid in a 5+ card side suit promises the Ace or King. For example, 1♠ - 2N! - 4♦ - 4♥ (control) - 5♦ shows the Ace or King of diamonds. Opener’s suit must be a good suit or he would have bid his shortness, so being able to show possession of the Ace or King is important.
  • Once you show a short suit, control-bid that suit only with a void, not a singleton Ace. An example would be a Jacoby 2N auction, with opener rebidding a stiff or void, such as 1♠ - 2N! - 3♦! (stiff or void) - 4♣ (control) - 4♦; this shows opener has a void in diamonds.
  • A control bid at the five level promises first round control, because 4N is no longer available.

Bergen gives this example of a five-level control bid:

West East

♠JT752 ♠AK643
♥AK982 ♥Q64
♦A4 ♦87
♣2 ♣AJT

The bidding is:

1♠ – 2N!
4♥ – 5♣ (not 4N here)
5♦ – 7♠

The 4♥ bid shows a five-card suit with two of the top three honors. Therefore East knows West has the AK in hearts. East makes the control-bid in clubs to give West a chance to show the Ace of diamonds; for West to immediately bid 4N would be wrong because of the worthless doubleton in diamonds. After knowing all suits are stopped, and foreseeing setting up the hearts for a diamond discard, East can see the tricks for the 26 HCP grand slam. We don’t promise this will happen to you, but it shows the power of the method.

Note that quite often preliminary control bids below the level of game allow us to bid 4N where we otherwise could not, or to avoid getting to the five level when we don’t belong there.

Bergen’s “Better Slam Bidding” and its workbook has excellent examples.

Serious 3N

When we have agreed to a major at the three level, and we are in a game-forcing auction, a bid of 3N shows serious interest in slam, and asks partner to start control-bidding. A failure to bid 3N shows no interest in slam, but a control bid shows mild interest in case partner has extras.

This convention is explained in more detail in Fred Gitelman’s article “Improving 2/1” at

Five Notrump Pick-a-slam

When we have not agreed on a suit but you determine that the partnership has the points to be in slam, a jump bid of 5N is a great alternative to just shooting out 6N. It is much, much easier to make 12 tricks in a suit, even a seven-card fit, than it is in no-trump.

In response, partner can suggest a suit to play in or bid 6N.