[pran]

 axman, on 2019-December-08, 09:28, said:

Don't know what your antecedents are. It is notable that if by some route that the OLOOT is rejected 57C3 makes it clear that the subsequent OOT play performs the function of lead. It also is notable that knowing both of declaring side's cards the only possible gain to the defenders to rejecting the lead is when it is important to declarer's RHO which card the LHO plays first.

Law 57C3 says "a premature play(not a lead) by declarer"

The effect of this is that when Declarer plays to a trick before his RHO and the lead to that trick was made by LHO or Dummy then Declarer's play may not be withdrawn regardless of which card RHO eventually plays to that trick.

However, if this play by Declarer is actually a lead, as is the case when Dummy's LOOT is withdrawn, then Law57C3 explicitly does not apply.

[Vampyr]

 pran, on 2019-December-08, 09:56, said:

Law 57C3 says "a premature play(not a lead) by declarer"

The effect of this is that when Declarer plays to a trick before his RHO and the lead to that trick was made by LHO or Dummy then Declarer's play may not be withdrawn regardless of which card RHO eventually plays to that trick.

However, if this play by Declarer is actually a lead, as is the case when Dummy's LOOT is withdrawn, then Law57C3 explicitly does not apply.

Yes, when it is not withdrawn, declarer’s card is not a lead.

[barmar]

 blackshoe, on 2019-December-07, 13:43, said:

Declarer leads from dummy. "You're in your hand" from one or both defenders. What is this? It's simply calling attention to an irregularity (lead out of turn from dummy).

While that's a correct literal interpretation, in my experience the intent of the speaker is usually that they don't accept the LOOT, unless they quickly amend it with something like "But I accept the lead".

[blackshoe]

IMO, if a defender says "you're in your hand" or the like to declarer, somebody should call the director. If a defender not next to play says "I accept the lead" his partner should play to the trick. If a defender next to play says "I do not accept the lead", dummy should put the card for which declarer called back amongst the yet-to-be-played cards, and declarer should lead from his hand. If dummy, after declarer calls for a card from dummy, says "you're in your hand", somebody should call the director.