Interference over the strong 1C opening

Interference at the one-level after 1C

Pass is used as a full positive, double as a negative, and bids as naturalish semipositives. This allows us to extract full mileage from injudicious interference, while getting in one descriptive bid early when the deal is likely to be only a partscore. The agreements are sufficiently general to deal with natural, transfer, multi-way or psychic overcalls. Relay-respose semipositives are no longer used - relay bidding is most effective for game or slam hands needing to transfer specific information, however once competitino has begun before any shape description has occured, the priority with semipositive hands should shift to insure competiting the partscore and exploring game are done effectively.
After the positive pass, in any auction, double by the hand under the presumed length is "action" style - indicating desire to penalise the interference if the other hand isn't unsuitable and has some appropriate trump holding. A double over the presumed length is close to a classical penalty action. If the level of the auction is sufficiently low (maximum loss of three steps) then both hands have a (level-adjusted) relay available as the cheapest bid, or higher bids as relay steps. Such elective relay shape-showing omits steps that show suits (but not fragments) that would have been able to make or accept a below-the-length action double. Thus the opponents' suit(s) may never be shown in elective relay shape-showing. A hand holding their suit must make a forcing pass, make a penalty or action double, or commit to relay asking. After a relay ask, the shapes RR may hold are any consistent with their previous auction and the relay structure will reflect this.
If the opponents have bid a denomination that they show, then the elective relay shape-showing agreement works fairly simply. However if the opponents have bid another denomination (e.g. a transfer overcall) then double shows an action double of the suit they have bid (as the presumed length in the suit is with the partner of the transfer overcaller), pass is noncommittal and elective shape-showing omits both the suit of the overcall and the suit of the bid used to show it. If the opponents have not yet shown a specific suit (e.g. a nonspecific two-suiter or other multi-way bid) then double of the suit bid is still for penalty or action according to which opponent holds the presumed length, and relay shape-showing omits only that suit.
Subsequently, if the level of the interference is too high for relays then action/penalty doubles and natural bidding apply. When the auction is at the two level and our side has not shown any shape (aside from any implied by doubles or passes), natural bidding is understood to include Rubensohl. If the opponents run from an action or penalty double, the same above agreements are still in force in the new situation. When a hand is unable to make or accept a double or to make a waiting pass, then the above agreements apply, with (level-adjusted) relays available in auctions sufficiently low.
After the initial negative-showing double, doubles by both hands are takeout and bidding is natural (Rubensohl where appropriate).
If the opponents interfere with 1NT, responder's double indicates penalty interest and activates action doubles, bids are natural (no Rubensohl; two-level bids are limited, three-level bids are forcing) and pass is negative.

Example Auctions over 1C

After 1C - 1H - Pass - Pass

Dbl Action (including most hands with 4+H)
Pass
Pass Accepting with suitable hand and trump holding, e.g. Jx or better
1S Game-forcing relay
1NT 4+S 0-3H (note heart step omitted)
2C 4+D 0-3S 0-3H, etc.
1S Relay (tends to deny four hearts)
1NT 4+S 0-3H (note heart step omitted)
2C 4+D 0-3S 0-3H, etc.

After 1C - 1S - Pass - 2S

Pass Takeout/Waiting (relays broken)
Dbl Action
2NT+ Rubensohl, etc.

After 1C - 1D - Pass - 3D

Pass Takeout/Waiting (relays broken)
Dbl Action
3H Natural and forcing

After 1C - 1H - Pass - 1S

Pass Takeout/Waiting
Dbl Penalty
Pass
Pass Accepting
1NT Relay (extreme measure)
2C 4+H 0-3S (note spade step omitted)
2D 4+D 0-3S 0-3H, etc.
2H
Pass Takeout/Waiting
Dbl Penalty
1NT Relay
2C 4+S unsuited for penalty
2D 4+H 0-3S
2H 4+D 0-3S 0-3H, etc.

After 1C - 1H - Pass - Pass

Dbl Action (including most hands with 4+H)
1S Relay
1NT 4+S 0-3H (note heart step omitted)
2C 4+D 0-3S 0-3H, etc.

After 1C - Dbl! - Pass - 1D (Dbl TWERB, showing D or majors)

Pass Takeout/Waiting
1H Majors
Pass Takeout/Waiting
Dbl Penalty
1S Relay
1NT 4+S 0-3H
2C 4+H 0-3S
2D 4+D 0-3S 0-3H, etc.
Dbl Action (including most hands with 4+D)
1H Majors
Pass Takeout/Waiting
Dbl Penalty
1S Relay
1NT 4+S
2C 4+H 0-3S
2D 4+D 0-3S 0-3H, etc.
1H Relay
Pass
1S 4+S
1NT 4+H 0-3S, etc.
1S 4+S 0-3D
1NT 4+H 0-3S 0-3D
2C balanced with 4-5 card major, etc.

After 1C - 1NT

Pass Unsuitable for penalty, activates action doubles
Dbl Penalty interest, activates action doubles
2C Natural, limited

Interference at the two-level after 1C

Double by either hand is takeout-oriented. Bids by either hand at the two level are natural and limited. Bids at 2NT or higher either directly or after a takeout double are Rubensohl. There are many kinds of auctions beginning with strong pass that will leave the auction at the two level with relays not having begun and neither hand having shown shape. In all such auctions, direct Rubensohl and Rubensohl after partner's takeout double applies to both hands. When the auction is at the two level after relays have begun, see below.

Interference above the two-level after 1C

Double of suit bids that show (or could have) the suit bid is takeout through all levels, and bids are natural (except 4NT 2-suited takeout). Double of notrump bids indicates penalty interest of whatever the notrump bidder showed and activates penalty doubles. Double of bids that deny the suit bid indicates penalty interest and activates penalty doubles, and bids are natural (except 4NT 2-suited takeout).

Interference in Relay Auctions

Relays have begun any time the unlimited hand makes a call that is for relay (game-forcing or invitational or better), or when a positive response is made to a 1C opening or when a semipositive response is demanded (e.g. 1C 1H 1S). We differentiate three cases of interference: that at or below 1S, higher interference that causes a loss of at most three steps in the subsequent relay structure, and higher interference that does causes a greater loss.
Interference at or below 1S is treated using agreements similar to that described above for one-level interference over the strong pass. Both hands have action/penalty doubles available with relay asking and showing following in the usual manner, except in no case can a hand whose strength is limited demand shape from an unlimited hand. Also, a hand that has already denied a holding sufficent to make a penalty or action double may double to show their maximum possible holding, e.g. honour-third. Relay shape-showing is done in the context of the previous auction, with simple deletion of steps that show hands that can no longer be held because of constraints from not having attempted to penalise the opponents.
After interference above 1S, R's double and redouble in both direct and pass-out seats are for penalty. If the interference (by either opponent) is such that RR may bid steps that are at most three steps above normal, then level-adjusted relays are used. Note that RR will have a double (or redouble) or both a double and a pass (or a redouble and a pass) available as a relay step, depending on the position of the interference. If the interference raises the steps more than three steps, then both R and RR may double for penalty. If the relay-breaking interference occurs at the two-level then both hands have Rubensohl available, both directly and after a penalty double by partner. If the relay-breaking interference was at 2NT or higher, then both hands bid naturally in the context of the preceding auction.

Example Auctions with Interference during Relays

After 1C - Pass - 1D

1S Natural
Pass Waiting
Pass
Dbl Action double of spades, including all hands with 4+S
Pass
Pass Enough trump help, e.g. honour-doubleton or three small
1NT Game-forcing relay
2C 4+H 0-3S
2D 4+D 0-3S 0-3H
2H Balanced 4-5H 2-3S
2S Balanced no major
2NT Three-suited short spades, etc.
1NT Game-forcing relay
2C Balanced 2-3S (Note: 2D is now just a game-forcing relay)
2D Two-suited with 4+H 5+D
2H Two-suited with 5+H 4D
2S+ One-suited with 6+H, etc.
Dbl Penalty of spades
Pass
1NT Game-forcing relay (rare action) - normal relay structure used, despite the inefficiency
2C Balanced 2S (extremely rare)
2D Two-suited with 4+H 5+D
2H Two-suited with 5+H 4D
2S+ One-suited with 6+H, etc.
1NT Game-forcing relay
2C 4+H 0-3S
2D 4+D 0-3S 0-3H
2H Balanced 4-5H 2-3S
2S Balanced no major
2NT Three-suited short spades, etc.
1H TWERB (spades or both red suits)
Pass Waiting
Pass
Dbl Penalty double of hearts
Pass
Pass OK
1S Game-forcing relay (rare - full relay structure used)
1NT 4+S 0-3H
2C 4+D 0-3S 0-3H
2D Balanced 4-5S 2-3H
2H Balanced no major
2S Three-suited short hearts, etc.
1S Game-forcing relay
1NT 4+S
2C 4+H 0-3S
2D 4+D 0-3S 0-3H
2H Balanced with a 4-5 card major
2S Balanced no major
2NT Three-suited short major, etc.
Dbl Action double of hearts
Pass
Pass Enough trump help, e.g. honour-doubleton or three small
1S Game-forcing relay (rare action) - normal relay structure used, despite the inefficiency
1NT 4+S 0-3H
2C 4+D 0-3S 0-3H
2D Balanced 4-5S 2-3H
2H Balanced no major
2S Three-suited short hearts, etc.
1S Game-forcing relay
1NT 4+S 0-3H
2C 4+D 0-3S 0-3H
2D Balanced 4-5S 2-3H
2H Balanced no major
2S Three-suited short hearts, etc.

Interference in Variable Captaincy auctions

Interference when relay captaincy is undecided requires more specialised treatment than interference in the normal fixed-captaincy relay auctions. Indeed, this complexity is the chief cost of using the method. Fortunately, complex continutions only occur frequently after non-jump interference by fourth hand after the lowest positive response by the initial responder. Further relays are available only if the resulting structure will be able to show all unbalanced hands in its structure at most three steps higher than the corresponding noncompetitive auction. Defensive-oriented doubles are always be available and always break further relays. Depending on the position of the intervenor, passes may or may not be descriptive in constructive or defensive senses in order to cater for the hand types possible for the two hands.
If the intervention relates to a specific suit or suits (e.g. a natural bid, a transfer, an anchored unusual notrump, or a lead-directing double), or is the subject of no agreement, then the following two provisions apply:
When the 1C opener is in the direct seat over intervention, they have three actions available:
Pass Shows a balanced hand without decent 4+ length in their suit (or a demand ask hand), and becomes R. RR then makes an "action" double with all hands with 4+ length in their suit (which R may or may not pass, but in any case further relays are off), or gives relay responses with bids showing 4+ length in their suit omitted simply from the structure.
Dbl Shows 4+ length in their suit, with decent suit quality if balanced, and further relays are off.
Step 1+ Shows an unbalanced hand with 0-3 cards in their suit, and becomes RR.
When the hand that responded 1D initially is in the direct seat over intervention, they also have three actions available:
Pass Shows a balanced hand without decent 4+ length in their suit (then 1C opener's double is for penalty - breaking relays - and Step 1 is for relay (including demand ask) and Step 2+ are relay responses showing unbalanced hands with bids showing 4+ length in their suit omitted simply from the structure.
Dbl Shows 4+ length in their suit and interest in defending, with further relays off. A balanced hand with bad 4+ length may choose to show shape, as below.
Step 1+ Shows an unbalanced hand using the full remaining unbalanced structure, including any bids that show 4+ length in the opponents' suit(s).
If the intervention is unrelated to a specific suit (e.g. a TWERB- or TOXIC-style action, a wonder bid, or agreed to be a random action) then either hand may elect to pass non-descriptively (including all balanced hands and all hands more interested in defensive possibilities than description), or to show an unbalanced hand with steps beginning with Dbl (which evidently does not break relays) with no omissions from the remaining unbalanced relay structure. Once a possible contract has been named subsequently, then direct seat actions are as above. Should such a nonspecific intervention by passed by advancer, then 1C opener is arbitrarily determined to be R, and the hand that has to bid now has a penalty double (which breaks further relays), and either a Step 1 relay ask (by R) or Step 1+ relay responses (by RR).
In any auction where relays are off, Rubensohl and a defensive-oriented double are used.

Rubensohl

Rubensohl is a convention similar to Lebensohl that utilises all the bids from 2NT through 3S in a transfer sense in order to give great flexibility to hand description in contested auctions. When Rubensohl is available, two level bids are natural and limited. Other bids are:
2NT Transfer to clubs
3C Transfer to diamonds
3D Transfer to hearts
3H Transfer to spades
3S No major suit, no stopper for notrump, at least game values.
3NT No major suit, appropriate stopper, game values.
4X Natural
The following principles apply: