Vampyr, on 2017-January-12, 00:14, said:
Yes, one strange aspect of the ruling was that the players had not discussed their requirements for a 2♣ opener, had not seen each other bid one and had not, in fact, ever played together before. Opener was not sure whether she had ever knowingly played Benjy previously. Yet the players were assumed to have an agreement.
As I've mentioned in numerous other threads, the laws on disclosure and MI are based on a presumption that pairs actually
have reasonably firm agreements that can be disclosed. In individuals, or with pickup partners who have not had extensive discussion, their agreements are often vague to nonexistent. They'll frequently just agree to a convention by name, or check off a box on the CC as they fill it out, but that doesn't mean their understandings of it are consistent.
It's difficult to apply the same disclosure rules as we would for regular partners. And maybe it's not even fair to attempt to do so. The spirit of full disclosure is that the opponents should have about the same information as the partners, so if the partnership is not on the same page, the opponents are not really disadvantaged. Although when a player hears his partner's explanation, he'll be aware that they have a misunderstanding, while the opponents have no way of knowing that something is amiss. The laws say that he should eventually reveal that his partner made a misexplanation, but since they didn't actually have an agreement, he could avoid this by deciding that his bid was the mistake, not the explanation. As long as he doesn't use the UI from the explanation in his further bidding, it's probably all legal.