Unauthorised information may not be used to choose an action, ie a call or play. That is a matter of Law.
However, nowhere does it say that UI may not be used to help give correct information or to correct MI. Thus if a player knows he has gone wrong from his partner's explanations he may not use this information to make the best call for the rest of the auction, but he should explain his partner's calls correctly.
The matter of whether you can change an unintended call or play based on UI is what was discussed at the L&EC. The obvious case is where you open 1
♠ and partner announces "Twelve to fourteen": obviously you have accidentally pulled the 1NT card out. You could read the UI Laws to say that you are not permitted to change it because your choice of call would then be based on UI.
It was decided informally to find out the position elsewhere. Max Bavin wrote to many people around the world: I wrote to a lot of people. The answer was unanimous: everywhere would allow such a change.
The reasons for allowing such a change included some, eg the ACBL, who read the Laws to allow it. But the vast majority were of the view that whatever the Laws say, it would be impractical and making a mockery of the reasons for Law 25A not to allow such a change. This view was expressed by people in the USA, Germany, Japan, Australia, France, Italy, Croatia and elsewhere.
If I was still a member of the L&EC I was intending to suggest that we accept that such a change to an unintended call is permitted, ie however it was discovered, without giving a legal basis. I expect that I shall write to them to express this view.
barmar, on 2011-October-28, 09:26, said:
And if that had happened, we'd probably be dealing with the controversial issues of whether his partner's alert is allowed to get him to notice this and when the "pause for thought" clock starts. Although if he corrects his inadvertent bid before the next player calls, I think this is a good example of why this should be allowed, as it's a "no harm, no foul" situation and they get to play real bridge.
I have never known any authority whatever that is in doubt as to when the pause for thought starts, and I do not believe it is controversial. In my view it is unanimous that the clock starts from the realisation of when the call is wrong. Even if it were not unanimous, the fact that we have a WBFLC minute saying so would surely suffice.
Furthermore, even if were not unanimous, what other interpretation is possible? How can it be a "pause for thought" before realisation?