[duschek]

Screens in use. South was dealer and opened 1♦, West passed, and South passed on the tray. However, the 1♦ bid fell off the tray, so that it appeared to North and East as though West had passed first-in-hand. North passed, East bid 1♥, and the tray was passed back to South and West, who now discovered that the 1♦ bid had stayed on their own side of the screen all along. Everybody has seen the calls made by North and East; South and West knowing that North and East bid on false assumptions. Director!

Some considerations:

• South is at fault, since he is burdened with the task of passing the tray.
  
• West should probably have discovered the error too, the 1♦ card lying on the table on his side of the screen.
  
• North and East are responsible for discovering calls out of turn, so should both have discovered the error.

[mrdct]

Under all of the screen regulations I've ever played under it is solely the responsibility of north-south to look after the bidding tray and ensure that it correctly passes under the screen with a complete record of the auction thus far. Accordingly, I'm going to treat NS as the offending side here in that south didn't pass the tray through properly and north didn't check the completeness of the auction by reference to the board which I presume was on the tray.

Auction proceeds as if it had gone 1♦:pass:pass:1♥ with the fact the north and east based their bids on an apparent misapprehension that west was dealer being authorised info for west but unauthorised info for south who needs to proceed in the auction on the assumption that his partner couldn't find a response to 1♦. If at some point it becomes clear by authorised means that north has something else, such as by bidding 2♥ this round for example, then I think south can then legitimately play north for some values.