What's the contract?
Playing with screens.
North, who will be declarer in NT, bids 4NT (natural and invitational)
East passes
Tray passed under the screen
South considers matters for a while, and eventually bids 6NT
West passes
South and West, distracted by South's time spent thinking, do not immediately pass the tray under the screen but instead remove all their bidding cards from the tray. It is then pushed back with their side empty. North and East assume that 4NT has been passed out.
Note that technically the tray is supposed to be passed back showing the final passes before the cards are removed, although that very rarely actually happens. Thus all four players, and certainly both South and West i.e. both partnerships, are offending.
North and East play and score the hand assuming the contract is 4NT. South and West do the same assuming it is 6NT. As South was looking after the bridgemate, it is in the official result as being played in 6NT. The discrepancy is not noticed until after the end of the session (in the case of EW, until they were in the car on the way home; I don't know when NS realised). The correction period has not expired as there is another day to the event.
How do you rule?
In this particular case, it didn't affect either the play or the defence (although declarer might have taken longer over the play if he thought he was in 6NT). Does that matter?
Comments
I won't comment on possible procedural penalties.
Alan
Does your answer only apply to this instance when the play and defence were unaffected?
What if North was declarer both in hearts and in NT, and South had bid 6H, but North and East then played the hand assuming he was in NT? Here's a hypothetical hand I've just invented (the auction may not have made much sense but the principle is sound):
.............QJxx
.............AKxx
.............Kxx
.............Ax
AKxx..........................xxxx
xx...............................x
xxxx..........................xxx
109x..........................K10xxx
.............x
.............QJ10xxx
.............AQx
.............QJx
South has shown a singleton spade on the auction. South/West think he is in 4NT, North/East think South is in 6H
West leads the A and K of spades, and South claims 'the rest' without playing a card from hand.
North/East score it as 6H making (East feeling cross about West's defence). West/South score it as 4NT+1. NO-one realises until later.
If you the TD say that "6H would have been passed if proper procedure was followed so 6H is the obvious answer"
West will be very upset and say he would never play a second spade defending 6H (he wasn't interested in overtricks against 4NT) and South might not have played a heart on the second spade if he had continued playing.
WB 5.1.1p5 has the answer to this: it's N/S's responsibility to ensure that the auction is the same on both sides of the screen (N/S have the ability to enforce this by holding the tray until it can be corrected). So in either case, South is at fault for allowing the tray to be passed with calls missing. Technically we should therefore rule (in the original case) as though South changed their call from 6NT to Pass, but in this situation I think you can reasonably argue that West accepted the change of call.
Unfortunately, or rather fortunately, that regulation was changed for international events after protests from TDs at Wuhan this year, so it is now the responsibility of everyone to ensure the whole auction is visible. This means both sides were offending, which could in principle lead to a split result being awarded.
"international events".
Does that include the English Open Trials?
This observation does not solve the problem for the moment, just indicates what the laws/regulations could usefully say.
Law 36C says
This formula could be applied to other inadmissible calls (Law 37-39) so that the final contract is determined by the admissible calls. This formula could also be applied to incomplete auctions: when the opening lead is faced (and dummy is spread) the auction is over and the final contract is scored as if the auction concluded with the necessary number of passes.
This would allow a result to be obtained, avoiding Law 12C2. The director would still have to consider whether either side had gained through North or East not knowing the contract during the play (or for some hours after).