If I had to guess the most common infraction in bridge (and guess because I don’t keep statistics), I would say it is declarer leading from the wrong hand. He leads from Dummy when he won the last trick in his hand or the other way around.
Now I’m rarely called to the table when this occurs (the other night was an exception as I gave this chat before the game!). However, it is an infraction.
Before addressing the infraction, let’s revisit what Dummy is allowed to do.
Dummy is allowed to try and prevent declarer from committing an infraction. So if declarer is in his hand and starts to say “play…” or starts to raise his hand as if to point at the card he is about to call from dummy, Dummy is allowed to try and prevent this — usually Dummy pipes up with a quick, “You’re in your hand”.
Similarly, if declarer is in dummy and starts to detach a card from his hand, Dummy can say “You’re in dummy” (or words to that effect).
Once declarer has called a card from dummy or played a card from his hand, Dummy should say absolutely nothing. The infraction has already occurred.
What Happens Then?
Someone draws attention to declarer’s having led from the wrong hand. In theory, you should call the director. However, I for one (and I imagine most directors, at least at the club-level) will not be upset if you settle this one yourselves — but you must do so correctly (or I will get upset).
Many players appear to be under the impression that when someone points out to declarer that he has led from the wrong hand that he simply restores the played card (to dummy or his hand as appropriate) and then plays from the right hand.
This is wrong!
Just as when a defender leads out of turn and declarer gets a chance to accept the lead out of turn, so do the defenders when declarer leads out of turn. That shouldn’t really be a surprise — it is something all of you should know (this is a common infraction and the rules are straightforward).
Either defender (it doesn’t have to be the defender who would play next if the lead is accepted) can say, “I accept the lead” or “No, lead from the correct hand” (or words to that effect). Now this situation is no different than any other infraction where the result involves options — partners are not allowed to consult with each other.
That means, if you don’t call the director (which as I’ve said, the rules say you should), then the declarer should give the defenders an opportunity to voice a choice (one reason the director should be called is because many defenders will not know they have a choice).
By the way, if the director is called and neither defender speaks up, he (or she) will give them one more chance by saying something like, “If neither defender speaks up, declarer will be required to lead from the correct hand” (that is, follow correct procedure). The director will pause a few more seconds and, if neither defender says anything, tell declarer to lead from the correct hand.