Logical Alternative?
This situation was given to me.
Auction
2 !c : 2 !h
2N : 3 !d
5 !d : 5NT
AP
2 !h showed some values but not 3 controls
2N is a balanced 22-23
3 !d is a transfer to hearts (not alerted)
5 !d was bid after a long pause
5NT (-1) was the final contract - after review the TD ruled the score back to 5 !d -2.
Obviously the player must carefully avoid taking advantage of the UI (73C) but we do need to look at law 40a
- Information conveyed to partner through such understandings must arise from the calls, plays and conditions of the current deal. Each player is **entitled to take into account the legal auction **and, subject to any exclusions in these laws, the cards he has seen. He is entitled to use information specified elsewhere in these laws to be authorized. (See Law 73C.)
Since 5 !d is an impossible bid in their system ( 4 !d would show a good fit, slam interest and a cue in diamonds), I would argue that 5NT should be allowed since there are no logical alternatives.
Why do I say that?
Because law 16B says
(b) A logical alternative is an action that a significant proportion of the class of players in
question, using the methods of the partnership, would seriously consider, and some
might select.
At the point where the 5NT call is being considered (as well as pasing 5 !d or bidding 5 !h or even 6 !h) the partnership has no methods - thus no logical alternatives.
Or does 73C by itself force a pass (or a raise to 6 !d ) notwithstanding 40a.
Comments
It appears to me that the methods of the partnership concerning the 5 !d bid are that:
(a) it is not a normal response; and
(b) there is no agreement about what it means;
but not that there is an implicit agreement never to use it, so that responder can claim AI that duplicates the UI.
I do not like the proposition that "impossible" bids allow a partner in receipt of UI to "do what they like", although I can envisage situations where one might conclude that there was no infraction.
Another issue which might arise in this scenario is that it would be unusual for responder to bid 5NT in tempo (it is arguable that an "in tempo" bid of 5NT is pretty convincing evidence that responder has not taken the time to evaluate his responsibilities under L73C). There might also be "body language" from responder over 5 !d (or over the missing alert). If opener has UI from any of these sources, then his pass of 5NT might be subject to scrutiny. If he thinks that 3 !d is natural and forcing, then perhaps responder might have some freak (albeit without the three controls denied by the 2 !h response)...
Yes - I missed the possibility of the 5NT bidder passing UI. Although of course if the 5NT call is disallowed then it won't affect the ruling. Responder is now thinking : Why has partner bid 5NT (I assume they don't use it as 'pick a slam')? If it was conventionally a grand slam query then the contract should be 6!d or 7 !d - but again we are limited to 'methods of the partnership' rather than imposing our own ideas.
The text from the laws in bold above is a problem. Now can we ask that logical alternatives are based on the methods of the partnership when the unauthorised information (lack of alert) suggests partner has a different understanding of the methods of the partnership?
I think there are logical alternatives: give the hand and the auction and the fact that 3D was a transfer (and that this is screens/online, so we don't know if partner alerted 3D) and see what players call.
This appears to me to be a non-sequitur.
Anyway, the fact that this appears to be outside of partnership agreements shouldn't prevent you from polling other players "using the methods of the partnership". You just have to give them as much information as you have on their methods.
The question might go along the lines of "Your agreements in this situation are such and such, but you have no agreements w.r.t. that situation. What do you think partner is showing by his 5D bid? & what action do you take?"
If the answer to the first question is (almost universally) "clearly partner has (or I have) forgotten the system", and if none choose to pass, then you can probably allow 5NT to stand.
If the answer is "partner must have a string of diamonds and has chosen not to complete the transfer" then "Pass" may indeed be a logical alternative (& I suspect that this is the case).
The answer to the second question is the real test. But the answer to the first question might also help with determining whether some actions are suggested over others by the UI.
I think Mitch has put it very well. Essentially we are glossing the text of the law effectively to read "using the methods of the partnership, so far as they go".