[jerdonald]

BBO forum,
Declarer's LHO leads a non trump suit, dummy follows, RHO trumps
and declarer mistakenly under trumps, there is no revoke. Can
declarer take back the under trump card and play another?

This may belong in the ruling forum.

Jerry

[sfi]

Declarer played in turn with a card they were legally allowed to play. Why would they be allowed to change their card?

[jerdonald]

sfi
Declarer seems to have some leeway on penalty cards. For one
example, if declarer leads out of hand when it's dummy's turn
he/she is allowed to pick up the card and play another.

Jerry

[mycroft]

That's the difference between legal and illegal.

A play out of turn is an illegal play. A play of any other card, when unable to follow suit, in turn, is a legal play.

Illegal plays get rectified (note that Declarer can't just put the card back in his hand. The TD should be called; defenders have the right to accept the play; a defender could follow to the played card before declarer realizes he played from the wrong hand, dummy may have been the person pointing it out *after the infraction had occurred* (as opposed to before the card actually got played, within her rights as "attempting to stop declarer from committing in irregularity"); I'm sure I'm missing something. It's all in the Law Book (including the part where declarer does not get penalty cards). However, nothing in the Laws allows rectraction of a played card from declarer's hand, if it's a legal play (it does talk about cards faced that were not played, and also about inadvertent calls of a card from dummy, of course. For every rule, there is an exception™).

[jerdonald]

mycroft,
Thanks I'll go read the rules about declarer's card play.

Jerry

[Vampyr]

Not long ago I was dummy, and partner told me to "ruff". Unfortunately second hand had already ruffed so I had to play a smaller trump. It had never occurred to us that the card could be taken back - why would it? As has been noted above, a legal card cannot be retracted for any reason, unless a declarer "misspeaks" when playing a card from dummy. So, getting a trick ahead of yourself or thinking the better of the play and changing it "in the same breath" is not misspeaking; it is changing one's mind and is not permitted.

[kuhchung]

And as his cheeks turned bright red from the embarrassment of underruffing, the Rabbit had successfully set the stage for a trump endplay.

[EricK]

 Vampyr, on 2013-December-18, 18:50, said:

Not long ago I was dummy, and partner told me to "ruff". Unfortunately second hand had already ruffed so I had to play a smaller trump. It had never occurred to us that the card could be taken back - why would it?

This seems harsh to me. I've never heard anybody ever use "ruff" as shorthand for "underruff".

[blackshoe]

 EricK, on 2013-December-20, 14:38, said:

This seems harsh to me. I've never heard anybody ever use "ruff" as shorthand for "underruff".

Quote

Law 46B2: If declarer designates a suit but not a rank he is deemed to have called the lowest card of the suit indicated.

When declarer said "ruff" he is deemed to have called the lowest trump in dummy.