Interference Over One Club¶
Opponents are often anxious to bid something to interfere with your 1♣! opening, or after 1♣! - 1♦!. We in turn are anxious to take advantage of it.
Our guiding principle is to ignore their interference when we can, and to cue-bid their suit or double when we can’t respond normally.
Responses Over 2nd Seat’s Double¶
If they double after 1♣!, we split the negative bid into two ranges.
- Pass with 0-5 HCP. Assuming RHO bids, opener behaves as if they opened. Double is takeout, a cue bid is Michaels. A jump to 2N is Unusual.
- Redouble with 6-8 HCP or with a positive hand with no good bid. Doubles of their suit bid is takeout. Responder promises to bid once more.
- Suit bids are positive, game forcing, and show a five-card suit. Bidding proceeds naturally.
- 1N is a positive response with 8+ HCP and a stopper. It is game forcing. Reverse Stayman is on but not transfers (because if responder had a five-card suit he would bid it).
Responses Over 2nd Seat’s Suit Bid¶
If 2nd seat bids a suit at the one- or two-level, we follow the same general idea. Double can be 6-8 HCP or it could be a positive, balanced hand with no stopper. Responder promises one more bid.
Again, a new suit is a five-card suit with 8 or more points, game forcing. Our doubles are penalty now.
A bid of notrump by responder is game-forcing and promises a stopper. Reverse Stayman is on but not transfers.
A jump-shift is preemptive, 5-7 HCP with most of the points in the suit.
A cue-bid is a game-forcing hand with three suits, short in their suit.
Responses Over 3- or 4-Level Interference¶
Over 3- or 4-level interference, a double is game-forcing, but has no primary suit to bid below 3N. Opener can bid a 5+ card suit, pass the double for penalty, or try 3N. And of course, if responder bids a suit, it is a 5+ card suit and game-forcing.
Otherwise, with 0-6 HCP responder must just pass, and opener can pretend they have made a preemptive bid. Passing it is an option.
If opponents play transfer overcalls, treat it as if the target suit was the overcall.
There are conventional bids used to interfere with our opener. The three most popular are discussed in “Precision Today”.
Unless otherwise discussed, we use our normal defense to two-suited bids. A double ( or redouble) shows a positive hand with no suitable bid, usually balanced.
Mathe is the only system we have seen so far in practice. In Mathe, double shows the majors, and 1N the minors, at least 4-4. As in our general defense, (invisible) cue bids show a positive response in the corresponding suit, and direct bids of those suits are competitive (say 5-8 HCP or some shape).
Interference by 1N¶
A bid of 1N that was not conventional would be equal hand.
When by the opener’s LHO, responder’s pass or double as usual ought to suffice. If responder has more than 8 HCP, clearly the bid may well be a psyche or miscommunication (that is, it really is conventional but the advancer forgot to alert it).
Interference by RHO¶
If they intervene after 1♣! - 1♦!, generally opener acts as if they have opened.
- Opener passes with any balanced minimum.
- Double (or redouble) by opener is for takeout.
- Sometimes the responder with shortness in their suit doubles to protect an opener possibly holding a stack in their suit. Responder’s hand should contain four-card support for any unbid major.
If the opener’s RHO overcalls a positive response, bidding is natural and doubles are penalty oriented.
Interference Over Asking Bids¶
Asking bids are those that request step responses: CAB, TAB, and Beta. We use a uniform system to deal with interference to such bids:
- Double! / Redouble! is the first step
- Pass! is the second step
- The next available bid is the third step, etc.
For example, in the auction 1♣! - 1♥! - 1♠(Beta), suppose LHO suddenly bids 3♥. In that case 3♠ shows the third step.