National team event with screens. Lead ♣6; Table Result 3NT=
North explains 2C to East as 5-card stayman, South to West as normal Stayman. 2D is explained by North to East as showing a 5-card major. South does not alert it. North then explains 3H to East as to play in 4H if that is South's suit. It is now explained by South as Smolen, showing 4 hearts and 5 spades.
The relevant part of the referee ruling, and I have the full text, leaving the table result unchanged, was:
North/South’s system notes are clear that their methods are as described by North to East, and this is the information that West is entitled to when deciding on his lead. West is not entitled to know that the opposition have had a misunderstanding (White Book 8.21.2). On that basis (the systemic meaning is that South has shown five spades), West would not have led a spade, and therefore there is no damage. There was also no damage arising from East/West being at cross-purposes due to different explanations on the two sides of the screen.
There was a fine of 1VP to NS for not completing the convention card correctly (the actual methods were only in the system notes) but I wonder if the White Book is correct on this subject. West is indeed entitled to the knowledge that the systemic meaning of 2D is showing a five-card major, and that 3NT systemically denies that it is hearts. However the answer to any questions, or the volunteering of information under 20F1 is clearly AI, and West can make use of that in deciding his opening lead. The principle should be, and here I think the White Book is wrong, that the player can use the answers he gets at the table, but he also has a properly completed convention card to consult. If the convention card had been completed correctly, it would have been blindingly obvious, even for RR, that a spade lead was going to be successful. What the White Book does, by offering the opinion (completely absent in the Laws) that you are not entitled to know that your opponents are having a misunderstanding, is to discourage completely filled in CCs.
The referee writes:
The only way West would find a spade lead is if he had partial MI – knowing what each player had. Without screens, he might have been able to deduce this (at his own risk) from the timing of the explanations, but this is not information to which he is entitled, and it is not available with screens.
I dissent, as they say in the Court of Appeal. Another way West would find a spade lead would be if NS had a correctly completed convention card and he received the same information as he did at the table but saw that there was a different explanation on the convention card. And he could then indeed have his cake and eat it. If he believed the explanation he was given and it was wrong, he would get redress. If he believed the information on the convention card and it was wrong, he would get redress. The moral is to complete the CC correctly and give correct explanations!