South plays 6 spades. The ♦9 is hidden beneath the 7.
Lead of a small diamond to the Ace. Declarer proceeds to ruff two diamonds in dummy and then claims his contract. While North gathers up his cards the ♦9 is revealed. What now?!
This was a much debated TD-exam question in Holland, of which I thought that finally one view had been universally accepted. But not so...
View 1: Applying Law 64C we allow declarer to embark on a different plan had the ♦9 not been hidden. Playing a diamond in trick two is now clearly ridiculous. Adjusted score: 50% of 6♠-2 and 50% of 6 ♠= since declarer has no way of knowing on which AKQ combination he can discard his losing diamond.
While this solution feels most like a result had no infraction occurred it has a flaw: the result of the ruling will differ according to the moment that the ♦9 is discovered. Had the 9 come into view on ruffing in trick two then declarer would have been down one.
View 2: We apply Law 64C to the moment of the revoke and not earlier: that South would never had played a diamond in trick 2 is irrelevant, more so as NS are the offenders here. So declarer loses a diamond and the Ace of spades.
What do you think?