Unauthorised information to Keycard
I was called to the table at a club duplicate after the bidding sequence:
N S 1C 1H 2H 4N
North announced that 4N was “14-30” and bid 5C to show 1 or 4 key cards. South bid 5H followed by 3 passes
North is a below average standard club player and north-south were an unfamiliar partnership. North has been playing for at least a few years.
I explained that N announcement was UI and, as I wanted time to consider my ruling, to play the hand and for EW to call me back if they thought they had been damaged. I explained to North that she should not announce the responses to Blackwood
In the event, S misplayed the hand for -1 and a top for EW so no adjustment was necessary. I decided that a warning for N was enough on this occasion rather that a PP.
My question is, without the UI S would have had to guess whether to bid 5H or 6H. If S guesses correctly (e.g. in this case by bidding and making 5H) do I adjust the score to the least advantageous to NS (6H-1) (16B); or do I award a AAS of 60-40 to EW under Law12C
Comments
You should be sympathetic to the non offenders, but not to excess.
If you're not sure what the adusted score should be, you should award an assigned weighted score rather than an AAS - you know what the outcomes might be, you just don't know which to choose.
Depending on S's hand, you might award 50% 6H-1, and 50% 5H=.
Law 12C1c
If there was an adjustment here it would be on the basis that South might have bid 6H so should be 6H-1 rather than an artificial adjusted score.
You have to consider whether 5C might be taken as some other meaning and whether or not South might bid differently without being told 1 or 4. It does seem to me unlikely that thinking 5C is 0-3 rather than being told it's 1-4 would lead to South not bidding 6, the converse is more likely.
Even if NS had written down the RkCB was "14-30" and South has remembered, South still has the UI that North has remembered. But there is probably no logical alternative for South to play North for the 'correct' number of aces - according to what South remembers is the agreement.
If there is no agreement, given the UI, South must bid as if North's responses in not "14-30" and is "3041" or 0/4,1,2,3 or not blackwppd response at all.