RMB1

If the insufficient bid is accepted (Law 27A) it becomes part of the legal auction, and is authorised. It is explicit in Law 27B1(a): "Law 16D does not apply ...". It is probably deemed irrelevant in Law 27B1(b): because the AI from the replacement is the same (or more preciese than) any UI from the insufficient bid. In Law 27B2 and Law 27B3, any UI from the insufficient bid is irrelevant during the auction, and there are lead penalties; but there is no explicit statement on UI from the insufficient bid. +1 A more practical law would be much easier to formulate if the insufficient bid was unauthoried.

It is possible that you got the correct ruling, even if the TD's approach is not one we would recognise as always arriving at a ruling we would agree with. It is certainly possible that local interpretation is to assume that insufficient red suit bid is a transfer, and that any transfer has the same meaning as a sufficient transfer to be a non-barring call under Law 27B1(b).

Many players, and many who to aspire to direct, fail to realise there is rationale for the rules (= laws and regulations).

Only last month, I overheard (as TD) a pair proudly announce that 2,3,5,7 were encouraging.

A minor point (and probably irrelevant to this ruling): At this point did you make any ruling (to the table) about whether North would be silenced if South did get to bid 4♥? (I do not think you should.)

I was asked about a similar problem a few days ago; but not from the same country as the OP. Both board sets were boards that had not been played before (feed in to a Howell) and the director had put the wrong set on the table, and neither side checked the guide card. In this case the director had many options open to him (the best being to play the movement with the boards sets swapped over) but he cancelled the results on three boards and gave less than average plus to the pairs at the table. To answer the question in the topic title, if neither pair were not stationary (often the case at the feed in table in a full Howell) then the North-South pair arriving at the table are no more responsible for playing the correct boards than the East-West pair. That is to say, all the players were equally responsible.

I don't get this at all. At bridge the only things you do that should be to your advantage should be your choice of calls and plays. Everything else: how you make your calls or plays, now you explain, how you interact with the opponents, etc. should not disadvantage your opponents; and in most cases should err on the side of being helpful to the opponents.

Yes you can pass, as others have said. If you now remember that partner has forgotten before, or you remember other partnership experience that suggests that partner might have other than what you explained, then that is a disclosable partnership understanding. You should call the TD and explain that your previous explanation of 2♠ was an accurate description of your partnership agreement but was an incomplete description of your partnership understanding (or something less pompous sounding:)).

I think StevenG wants the power to ban bidding 2♦ with a weak hand with a six card major , even if your agreement is that 2♦ is not systemically Multi (so that 2♦ is a psyche/misbid).

Dummy may ask but not under the law in the OP about preventing an irregularity (Law 42B2). The irregularity (possible revoke) has already happened, so asking is not an attempt to prevent an irregularity. Instead there is are other laws that allows dummy to ask "having none?".

I wasn't being too serious: I was intending 3NT as to play, based on a long minor, and ambivalent about outside stops.

3NT?

I don't really understand your point. The word "unexpected" has been in the EBU alerting regulations for decades. Alerting unexpected meanings is not a recent change or interpretation. A practical test for "unexpected" is to ask some players.

If I did not so rule, it would be because a singleton ♥ is not unexpected (for a 1♠ = 2♥ = 2NT rebid). To rule, I would have to determine whether this is or isn't [un]expected.

I don't want to. Explanations are given in natural language (a dialect "bridge english"). Natural language contains assumptions, and speakers and listeners make assumptions. Players are not always speaking the same language, and make different assumptions, and misunderstandings occur. Players can avoid some misunderstandings by being aware of different meanings and assumptions used by other players. Misunderstanding between explainer and opponents happen. If the misunderstanding is the fault of the opponent then the opponent has no redress but if the misunderstanding is the fault of the explainer then there is misinformation. In this case, a 2NT rebid explained as "15-19" is taken to mean "like a traditional 2NT rebid but the range is wider: 15-19". The explainer should have been aware of this and should given a different explanation: 15-19, not necessarily traditional 2NT rebid shape".

Yes (weeks ago when I was consulted on this ruling) Is this rhetorical? I thought there was only one possible infraction. North is arguing that he was misinformed by the explanation: the infraction (if there is one) is misinformation.

It is not clear that an explanation was ever asked of 4NT/5♥. Even if ♠10 is a serious error, Law 12C still requires we consider an adjustment for offending side. Is the serious error unrelated to the infraction?

You so don't want to go there "strong" = "extended rule of 25" = a little better than an average hand and a bit of shape :)

Yes, if only implicitly (by omission). The laws say that declarer is responsible for choosing cards to play from dummy but otherwise dummy's cards remain the responsibility of dummy. Law 7 says that players are responsible for their own cards and no law says other players are responsible for dummy. In particular, Law 41D tells dummy how to display his hand: failure to do so properly (e.g. so that not all cards are visible) is breach of procedure and if so damages the defenders there can be rectification/adjustment.

It appears that there is no partnership understanding of 2♦: if 2♦ is explained as "no agreement" then East will stop bidding diamonds when it most convenient for him to do so. North has UI from the explanation of 2♦. If 2♦ is natural, 3♠ sounds like a very good hand, so 4♠ is a logical alternative to Pass by North; and Pass is suggested by the fact that the UI suggests South thinks North has support for ♠. East/West might double 4♠ especially as the explanation "no agreement" might suggest a wheel has come off. I will leave it to others to weight the number of tricks in 4♠ and rule 50% of that weighting in 4♠ and 50% of that weighting in 4♠X.

[pointless "me too" deleted]

I assumed that 3♠ was forcing for responder, when 1♥ was natural, but opener would not treat 3♠ as forcing, when 1♥=♠.

If 3♠ is a LA then I think everything else is suggested because you might play there when it is the wrong level and the wrong denominaion. But I think many of your listed alternatives are not LAs.

I think that this was a claim and that the play of ♥A is not normal so the last two tricks to the defence (= making 10 tricks). Lamford would have ♥Jx in the hidden hand. :)

You would be surprised by what goes on then. Certainly amongst the top directors, if we get rung up for a judgment ruling during a match then we invariably ring at least one other national tournament director, even if we think the ruling is obvious. We might also ring an EBU referee (or a household with more that one) to consult, in the way that we might consult a player. The whole process takes some time, which is why the TD may appear slow in getting back with a ruling. We also do this if we are the only director (or even one of two) at an event.