Authorised or not?
I was asked a nice question yesterday.
We are quite clear that the 'stop' card is not a bid, but its use out-of-turn (or its use and immediate retraction) provides UI to partner.
Now try this one.
Partner is dealer and is is mid-opening-the-bidding, having got as far as 'playing' the stop card, when RHO passes out of turn.
Is partner's aborted stop-bid AI to you when (i) deciding whether to accept the POOT, and/or (ii) if you do so, in the subsequent auction?
(for example: if you have a good and/or very defensive hand, you may well want to accept the POOT and open in front of partner to stop him pre-empting; if he had a strong opening you are unlikely to go wrong if you open; if you have a weak hand you want to let him pre-empt and make it very hard for 4th seat)
Argument for: it is your opponent's infraction that led to 'flapping' stop card, and hence you are the NOS
Argument against: if partner had said "I want to pre-empt" before opening the bidding, and then RHO had opened out of turn, I suspect we'd all say that was UI. And you can prevent the UI by not accepting the POOT.