In Duplicate bridge, there are two situations whether or not bidding boxes are used, and because they are so different, the TD should be immediately called (hopefully before West tells us what he "should" have bid).
If West misspoke - he meant to say 2
, but 1
came out of his mouth - then he is allowed to change the bid until partner calls, provided the announced wish for change (or change attempt) is done immediately upon him noticing (the Laws say "without pause for thought" - note that this is not the same as "without pause").(Law 25A).
This is why you call the TD immediately - it is her job to investigate and determine whether the conditions for "inadvertent call" apply.
If it is ruled inadvertent, and attempted to correct "without pause for thought", North not only may, but must retract her call, and call again to the correct opening. Of course, there's nothing saying she can't pass again!
If West has changed his mind - if he meant to say 1
, no matter what pigs flew by that caused him to want to, or if the TD decides that he did "pause for thought", then Law 25B applies. Since North has called, West can no longer change his call, 1
-P- stays the legal auction, and the fact that West wanted to open 2
is unauthorized for West's partner - he may not make a call that caters to west being light (if 2
would have been weak) or strong (if 2
would be strong) or strange (if 2
, or 1
, for that matter, was artificial) unless no other sensible action exists (and yeah, the TD has to judge on that as well.) Here, although North cannot change her pass, she (and South) *are* allowed to use the information that west wanted to bid 2
, at their own risk.
The rubber bridge laws are similar, but not identical (after all, there is no TD to make judgement rulings, so...) You can read them here (Laws 24, 25, and 26).