lamford, on 2015-July-16, 03:34, said:
A distinction must be made between the requirement that the player must play this card and information that the player has the card. Initially the underlead from KQJx to partners Ax is allowed, but subsequently the Director may decide that 50E3 applies.
If a player benefits from underleading the KQJ, as in this example, whether by accident or design, then the TD should award an adjusted score. Effectively one cannot gain from the underlead as opposed to the lead of the king. I think there is a separate breach of Law 16, but all roads lead to Rome.
The minute continues:
The player must convince the Director that he has not gained from the information that the player possesses the card.
In this example, West would not be able to so convince the Director. I do not think campboy is correct that the test is whether the player gained from the original infraction. It is whether he gained from the knowledge that his partner possesses the card that matters.
Let us agree that we disagree.
I don't have the WBFLC minute at hand, but the way I remember it (together with the discussion and reasoning) a defender who realises that his partner must play a particular (penalty) card to a suit may freely use that knowledge when selecting which card in the suit he will lead or play (as the case might be) from his own hand.
It was particularly mentioned that he needs not lead or play a King only to see it "killed" by his partner's Ace, or his Ace to see it "killing" his partner's King in situations where such plays would otherwise be "normal".