The vulnerability should be E/W only vulnerable, matchpointed open pairs.
Table result 4NT N -4, NS -200
The facts. 2S was alerted as showing spades or both minor, (as part of the Suction convention) which West had forgotten. At the end of the play, the director is called and asks to see E/W convention card, which they say they have misplaced (this is the second session . They say they will be able to get hold of an electronic copy if necessary. They say there is nothing on it to say that they play suction over a strong 2C, but it does say that they play this defense over a strong 1C opening, and they say that they use the same over all strong artificial openings.
The ruling: As a TD is required to rule mistaken explanation rather than misbid in the absence of evidence to the contrary [I forget which rule this is - no doubt someone can enlighten me], the score is adjusted to 80% of 4S S making 10 tricks and 20% of 2S E X -5, NS +1400. (My note: the percentages may not be exact, it may be something like 75% 25%. I don't have the paperwork to hand).
EW decide to appeal. At the end of the session, EW are able to find their convention cards and the defense to a strong 1C is shown as "Suction (X = diamonds or both majors etc)". There is nothing specific about a defense to a strong 2C opening.
They also explain a detail of a hand played the previous day when they went for -1700 after the auction (2C) 2NT (P) 3S (X) when 2NT was intended as showing both minors whereas the agreement was it showed spades and diamonds or hearts and clubs.
South says that he felt that East and West were both being honest about their agreements.
The AC's ruling was to agree with the TD's ruling. Their comments were (roughly) as follows:
"We agree with the TD's ruling. E/W should point out that they sometimes forget this part of their convention."
Thoughts? I hope I have included all relevant information here. If I have missed something I will endeavour to correct it.
This post has been edited by barmar: 2013-December-30, 09:51
Reason for edit: fix vulnerability in diagram