Correct Interpretation of Law 21B
First a declaration of interest - this involved my side not disclosing a "no agreement" situation.
After an auction P - 2S X 3D - 3H - 3S - P - P - X - P - P - P: I revealed that my 3D was based on lead directing and spade support (this is not a partnership agreement): the director was called and offered my RHO the opportunity of changing their last pass - which he did - and the auction continued 4H - X - P - P - P.
Law 21B states inter alii "a player may change a call without further rectification for his side...."
So the question became: what does that mean. There are two possible interpretations depending on how you apply "further".
1) No more rectification is possible as the auction proceeds: i.e. whatever happens in the auction after correction cannot be amended - as both players now know the facts, but this does not affect rectification available to either party prior to the change of call.
2) No more rectification at all is possible since this rectification is "further" or extra to the call - so by changing a call, the player accepts for his side all the rectification that can be allowed following the misleading information - thus preventing any discussion of what their partner might have done after having called with the MI.
There are possibly similar situations e.g. after a OLOOT dummy puts down their hand - thus declarer loses their options, although this is a NOS situation.
Anyway - it seems that the first definition is correct. If you do change your call having been advised of the MI, it does not affect the rights of the partnership to redress, if you might not have been in that position when you did make the call.
Comments
My reading is that you are right with your Option 1. Where you wrote "further" I believe it should be "other" but I don't think that makes any difference.
\Law 21B3 says "When it is too late to change a call". I read that it applies to any of the opponents' calls after your 3D bid, up to and including your LHO's double.
I'm curious. At the end of the original auction, I presume you said something like "I believe my 3D bid should have been alerted. We have no agreement for the the bid but I believe it should show spade support and suggest a diamond lead if defending"? If so, then well done on disclosing.
Barrie Partridge - CTD for Bridge Club Live
Law 21B1(a) always applies to the last call made by the non-offending side (partner has not subsequently called) whether or not that call is changed. The phrase "without other rectification for his side" would always apply, and if that phrase applied to rectification for earlier calls made by the non-offending side, we would never adjust for misinformation.
My interpretation is that "without other rectification for his side" applies to rectification for damage for that last call, and Law 21B3 still applies to rectification of damage for earlier calls.
(My statement of interest - I have already given this opinion to the directpr.)
@Robin
Well we would adjust for MI if the last call ISN'T changed.
I agree with the comment (and the ruling) - but it would be better if the Lawbook read
"When it is too late to change ANY call....."
I am struggling to see why the director allowed a change of call, or why you announced the meaning of your bid.
I get a situation such as: "I thought we were playing CRO" - "No I don't play that", where director determines MI under 21B1(b).
But this seems more like "I'm making my bid in the hope that things will turn out OK" where partner can have no more idea what's going on than opponents. That bidding a suit suggests a lead is a generally accepted bridge principle / common knowledge, as is "I can always go back to my partner's suit".
Why does this cross the threshold?
The director was content to rule misinformation (either an agreement to play 3D as lead-directing with spade support, or "no agreement") rather than misbid, Law 21B1(b).