Can your own call be UI to yourself?
A player's hand is right on the edge of their notrump range, borderline between a 1-of-a-suit opening and a 1NT opening.
The player finally decides to open 1NT rather than 1-of-a-suit, but has a slip of the mind and plays the 1-of-a-suit bidding card that they were thinking about and rejected, whilst believing that they were bidding 1NT.
Partner doesn't give the expected NT range announcement. This unexpected lack of announcement is UI to the opening bidder, who looks at their bidding cards and sees that they bid 1 of a suit. Because it was a very close decision anyway, they're content.
Is the fact that opener has made an unintended bid UI to themself? If so, can it subsequently become authorised through actions of the opponents (e.g. if LHO overcalls in the suit that opener thought they had bid, and the meaning of the overcall makes no sense for a cue bid but does make sense for an overcall of 1NT)?
I think the relevant Law here is 16A1a, but I'm not sure how to apply it, and there's no relevant guidance in the White Book.
Comments
The answer to this is delicate. The situation is not obvious because of the wording of Law 25A3.
Partner's failure to announce or unexpected announcement is unauthorised information. You may use this information to correct an unintended call (Law 25A3). If you made an unintended call but did not correct it then you continue to have unauthorised information, and are not 'allowed' to know what call you made.
For what it's worth, I've found some discussion from the ACBL on this subject: http://web2.acbl.org/casebooks/2009SanDiegoCasebook.pdf page 38 and onwards. It seems that this is a very contested subject (and many of the ACBL commentary panel thought that it would be preferable for the laws in question to be clarified).
(And also, of course, the call isn't correctable unless you pulled the wrong card from the box as a consequence of, e.g., not gripping the card you meant to pull firmly enough – the reason you became aware of the incorrect call isn't relevant to whether or not you can correct it, but the reason you made it is.)
I raised this question with the WBFLC secretary some time ago so we can expect it to be addressed when the new laws are considered; if we are very lucky, maybe even before.