Anyway, he ran into a situation and asked me if I would give the ruling. Penultimate board, declarer is top class, dummy is playing his second game of duplicate in eight years, the defenders are two charming and inexperienced young ladies.
No-trumps, trick 12, LHO leads a spade, declarer knows that there is only one other spade out, the ten. Dummy has J9 of spades. So, does he finesse or not? He stops to think. At this point, dummy says "Dummy is good"! After which LHO puts her other card, the ♠T, face up.
Now, the problem is that the other two cards declarer cannot see are both winners. So, declarer argues, once he has thought about it, he must finesse, ie get it right, because if LHO had a non-spade she would have cashed it.
When I ask LHO she says that she knew declarer would get it right because her partner had already showed out of spades. Declarer says he did not remember that if it was true. At this point, with my head hurting, my table recalls me to play the last board.
At the end I consult with a very fine player who says that declarer would have got it right 100% of the time half-way through the afternoon session, but thinks that declarer could have got it wrong perhaps one time in ten at the end of the evening session.
Of course we should quote a Law but regrettably neither the club nor the TD have a Law book!
So what do you think?

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