This chapter covers what responder does after we open the bidding and the opponents interfere, either with an overcall or a double. Our general attitude is that opponents at this point are untrustworthy: psychic bids and misbids are common, so we mostly bid our own hands and do not fret about what their calls are supposed to show.
Over interference our transfer style stays on at low levels. A double shows "stuff": 5+ HCP with no suit worth transferring, usually a balanced hand. Below 2NT, a new-suit bid is a transfer, showing 5+ cards in the next suit up and 5+ HCP (a good 4-card suit is allowed); this is on through 2♠. When the opponents bid one of our suits, the first cue-bid we make is a game force. A double followed by a cue-bid is natural, showing a real suit. If the opponents jump the auction above 2♠, our new suits revert to natural and are forcing but never game-forcing; the first cue-bid is still a game force.
There is one Michaels exception. When opener's cheapest natural bid in a suit would land on a cue-bid of the opponents' suit, that bid is Michaels (a two-suiter) instead. For example, in 1♣-(1♠)-X-(2♠), a follow-up of 3♠ is Michaels, not natural.
The table below shows the direct responses over a 1♠ overcall.
X "Stuff": 5+ HCP, no long suit to transfer, usually balanced. 1NT Transfer to ♣, 5+ cards. 2♣ Transfer to ♦, 5+ cards. 2♦ Transfer to ♥, 5+ cards. 2♠ Cue-bid: the first cue-bid always forces to game.
Because our 1♦ opener says little about diamonds, competition can get awkward in the minors. Two guidelines help. Most doubles of a diamond cue-bid simply show diamond length, unlike standard practice where such a double is takeout; a support double still takes precedence when it is available. When notrump is not a sensible natural bid, we use it to separate a club hand from a hand with both minors.
Our system stays on after 1♦-(X), all the way until the opponents cue-bid diamonds; once they cue, we revert to natural bidding.
XX 4+ ♥, any strength. 1♥ 4-5 ♠. 1♠ No 4-card major: balanced or both minors. Responder pulls 1NT to show minors. 1NT One minor, competitive. 2C is pass-or-correct. 2♣ Natural, non-forcing. 2♦ Natural, non-forcing. 2♥ 6+ ♠, any strength. 2♠ Both minors, mixed raise. 2NT Natural GF, rarely used.
We play Landy: 2♣ shows both majors and everything else is natural.
X Penalty. 2♣ Landy: both majors, 5-4 or better. 2♦ Natural. 2♥ Natural, ♥. 2♠ Natural, ♠.
Fairly standard methods. Negative doubles apply with no upper limit; high-level doubles are more about strength than exact shape.
Note: this section reflects the 2021 notes and has not yet been reviewed with Tom, so treat it as provisional. Over a takeout double of our major we play the transfer-based structure below (shown here over a 1♥ opening).
XX 10+ HCP, usually no trump fit. Other bids do not deny 10. 1♠ Natural, 4+ ♠. 1NT Transfer to ♣, 5+ cards; may be preparing a raise of ♥. 2♣ Transfer to ♦, 5+ cards. 2♥ Simple raise of ♥. 2NT Mixed raise of ♥. 3♥ Weak, preemptive raise of ♥.
We have general defenses for most interference; where a specific agreement exists for a specific convention, it takes precedence. Over a natural overcall our transfers stay on through 2♠. A double shows values, 5+ HCP ("stuff"), and is never game-forcing. If opener rebids notrump, systems are on. A transfer into the opponents' suit is Stayman.
Beyond that, the framework is Ruebensohl over a major-suit overcall and Lebensohl over a minor-suit overcall. A double of a natural 2-level bid is penalty, except that a double of 2♣ is Stayman regardless of what the 2♣ bid meant. When the opponents show two suits, we switch to an unusual-over-unusual style. Over the opponents' double of our 1NT, redouble forces 2♣ so responder can escape to a minor, and direct bids are systems on.
We treat a 2♣ or 2♦ opener much like any other opener: negative doubles, and new suits forcing after an overcall. A double of our 2m opener is ignored; systems are on, including the +1 asking bid.
After an overcall of our weak two, doubles are penalty and new suits are forcing for one round. Over a takeout double we play Transfer McCabe: redouble through the raise are transfers (with 2NT still an asking bid), each either a way to escape into the next-higher suit or a lead-directing raise of our major. A redouble is a "green light" raise of the major and a jump to 3M is a "red light" raise; over a green-light raise, opener may compete further if it looks right.
Transfer McCabe also applies over the opponents' takeout double of our 3-level preempts. There are no other special competitive agreements.