[Shugart23]

Partner opens 1c and I make a mistake in my response and I actually realized my mistake before my LHO passed, My misguided partner behind an asking sequence searching for slam but instead of answering his first question (control asking) , I attempt to bail out at 3NT. Was I allowed to do this ?

[blackshoe]

Why would you not be allowed to do this? You have no UI.

[paulg]

Firstly, I assume that your mistake was not a mechanical error otherwise you would be able to change your bid if partner has not called. So you have to live with the wrong response.

The next question is whether you have unauthorised information from partner before you make your choice: for example, did partner alert your call when you did not expect it, or did your partner explain your response to the opponents stating what your call meant?

If you have no unauthorised information, you can do whatever you think is best to get yourself out of the mess you have created - you suggest that this might be 3NT and this would be permitted.

If you have unauthorised information, then you are not permitted to 'wake up' to your call being wrong even though you remembered - primarily because this can never be proved. You must carefully avoid taking advantage of this unauthorised information, which generally means that you must bid as if you make the call you wanted to make and response to what partner's bid would mean in that context.

For example (and I will use my system), suppose that your partner opens 1♣ and you respond 1♥ to show 4+ spades, forgetting that you do not play transfers with this partner and he assumes that you have shown 4+ hearts. He does not alert 1♥, which gives you unauthorised information, so you are not allowed to wake up to this.

Partner rebids 2NT, which in your transfer response system shows at least four spades and a game forcing hand, but in partner's system shows 18-19 balanced. If you take any action to make it likely that you do not finish in a spade contract, then you are likely to get ruled against. You should not alert 2NT, because you should only alert convention bids in the world where you are correct, not in the world that you are having to make bids.

It can be very confusing and my advice is: try and do your best but do not appeal when the director rules against you.

[mycroft]

Paul's answer is wonderful. I'm just going to highlight a couple of things:

• "unauthorized information from partner [includes] a remark, question, explanation, gesture, mannerism, undue emphasis, inflection, haste or hesitation, an unexpected alert or failure to alert..." Law 73C1, excerpted and edited, my emphasis. As he said, just because partner didn't say anything doesn't mean there was no UI - if you would expect them to have said something.
  
• "Try your best but don't appeal" - Probably right. Ethically, if you do your best and this time the director judges that you still used UI (or did the thing that someone using UI would have done, with a reasonable alternative available, yada yada Law 16), you are in the clear. They're probably right, though, so accept it and go on. Hopefully they explain what the alternative was, and why they ruled it logical (so you know better for next time); but even without that, they're probably right.
  
  Note that if instead you try to work out if you can "get away" with the call suggested by the UI, *even if the director or your opponents believe there was no LA*, you might be legally in the clear, but you have not been ethical (and can be penalized for it, see 73C2)(*)
  
• "this can never be proved" - yeah, and I guarantee you that there are many people who will say "I woke up on my own" (or the equivalent "I didn't notice any hesitation"). For many of them, they will even believe it. For several of *them*, it will be true. But there are the rest, and players already think we directors are gullible idiots who only do this because we can't actually *play*. So the Laws are written, as much as possible, so that directors don't have to rule on intent or thinking, just on actions and facts.

(*) Note that even if you are not, the reputation of being an angle shooter can be enough penalty even without a ruling *on this hand*. For those who "don't care about their reputation", fine, but that does mean that your opponents will call on closer to borderline "potential use of UI" hands because they know you're one who sails close to the wind. And some of those "closer to borderline" hands will turn out to be slam dunk rulings against you.