- A "short" 1C opening (playing 5-card majors and 4-card 1D)
- A 1D opening showing either diamonds or clubs (in a Strong Club system)
- A multi-way (e.g. Polish) 1C opening
These conventions can cause much confusion when they come up, if opponents have not properly discussed their defence. I have a defence which applies to all of them. (It doesn't apply to conventions which promise a suit other than the one bid, such as a 1D opening showing hearts.) The defence is called:
"Treat as Natural"
And it's very simple: the idea is our bids have exactly the same meanings as if their opening was natural.I do mean exactly. So for example, if they open an artificial 1C,
- (1C) : Dbl = take-out of clubs;
- (1C) : 2C = Michaels (assuming you play this over a natural 1C);
- (1C) : 1H : (1S) : 2C = cue-bid showing heart support.
Now, the main advantage of this defence is in being confident that we know what we are doing, not just with the overcalls but with all the continuations as well. But I believe it's also a good defence in the theoretical sense. It's important not to get carried away with crazy defences to these sorts of opening bids. The main weakness of nebulous opening bids is that they allow the defenders to get into the auction easily and reach their best spot. The opening side can't do much about this, because they are relatively unlikely to be able to make a pre-emptive bid before it is revealed what opener has. (Contrast this with a weak 1NT opening - made on a hand type often included in these artificial 1m bids - which often manages to keep the defenders out of the auction completely.) So we exploit this weakness by bidding constructively. Though having said that, it is also a good idea to make pre-emptive overcalls a little more freely than we would over a natural opening bid.
Of course, if you play the "Treat as Natural" defence you cannot show a hand with length in the suit bid by opener. Or at least, you can't show it immediately. If you hold this hand, you have to pass initially and hope to be able to show it later. This is, again, exactly what you would do over a natural opening bid, although the situation does not come up so often in that case. The general principle is that if a cue-bid on the first round would have been artificial, then a pass and later action shows length in that suit. So for example:
- (1C) : p : (1H) : p , (1S) : 2C = natural clubs, decent hand;
- (1C) : p : (1S) : p , (2S) : X = take-out of spades, implying some length in clubs.
However if partner has bid in the meantime then the situation may not be so clear. This sort of auction is particularly important:
(1C) : p : (p) : 1H , (p) : 2C
Is 2C natural here, or is it a good raise of hearts? Both meanings are useful. I have a trick for this situation, which is that when we pass over a minor opening and partner bids a major suit, bidding opener's minor is natural, but bidding the other minor shows a good raise of partner's suit - the reason being that if we had a hand worth a bid in the other minor, we could have overcalled on the previous round.
Of course, in the spirit of the "Treat as Natural" defence, all such tricks apply equally after a genuinely natural opening. Whatever you agree over natural openings also applies to the artificial ones, and vice versa.
All of this applies when you are on opener's right, as well. Not only that, if they play a 1D response to 1C which is a sort of negative or relay, we go ahead and treat that as natural as well. Though this does mean you need to know what you play in sequences like
(1C) : p : (1H) : ...
A sensible approach is to play 2C and 2H both as natural here, and that fits in well if 1C is artificial. On the other hand, when the response is 1D there is a lot to be said for playing 2D (or 2C, or both!) as Michaels. A double traditionally shows the two unbid suits, but I like to define it as "take-out of the suit doubled", i.e. take-out of hearts in the sequence above. This makes it clear that a response of 2C is natural, whereas 2H would be an artificial cue (even if LHO makes a bid). Indeed, all continuations are the same as if we had doubled a 1H opening.