iviehoff, on 2012-February-07, 10:29, said:
I think you have in mind L79A2 which says
"A player must not knowingly accept either the score for a trick that his side did not win or the concession of a trick that his opponents could not lose."
I would not describe this as a trick the opponents "could not lose".
I was thinking of the rule about if there is "doubt about the claim the director must be summoned". If you think the opposition should have made more tricks than they claimed on the only conceivable line, that is doubt no?
I once had a hand when I was learning, where declarer had counted their tricks wrong, when the declarer claimed "thats 11 tricks", when cashing their 4 winners was actually 12 tricks. I and my partner just pointed it out and they got their 12 tricks, but they could have lost extra tricks by playing their loser first so as to make 11 tricks. I am pretty sure my obligation is to call the director, but in reality I always just point out this kind of mistake and let declarer look at their tricks again. My somewhat rambling point being that surely doubt extends to declarer might make extra tricks, as well as might make fewer.
The physics is theoretical, but the fun is real. - Sheldon Cooper