Unnecessary use of Stop card
If a player places the Stop card on the table and (without withdrawing any other cards from the bidding box) then says "Sorry, I changed my mind what to bid, the Stop is not required", what is the correct procedure?
It seems to me, as the UI given is so vague, that all you can do is let the auction proceed and ask the NOS to call you again if they feel they have been disadvantaged - is this correct?
I know I read something about this in the new Laws but I cannot for the life of me find it now (partly because Stop Card and Jump Bid unhelpfully do not appear in the index as either main entries or subheads. As a professional indexer I would be more than willing to produce a revised index for a future edition).
Comments
The use of the Stop Card and the statement "I've changed my mind" are both UI. I would explain what that means to offender's partner - "you must not use the information from what partner has done/said". If I am a non-playing TD I would ask to be called back regardless - NOS are often not sure if they should call back the TD - and they don't anyway.
The laws are agnostic about bidding boxes - so "Stop Card" is not going to appear. The closest the laws get to "Stop" or "Jump bid" is "skip-bid warning" in Law 73A2.
Playing a Stop card on a bid that doesn't require it is UI.
UI is not illegal in of itself – only making use of it is – so there's no reason to do anything unless the Stop-carder's partner does something that's demonstrably suggested over another logical alternative by the UI. It may be hard to demonstrate such a suggestion unless there's only one plausible jump bid in the situation, or if all jump bids would have similar meanings. (For example, after 1!s, (Pass), Stop 2!s, it might well make sense to disallow a continuation from an opener with 14 HCP and 5=3=3=2 shape; in this case, in most bidding systems, passing is a logical course of action, and almost all jump bids by responder would have been stronger than their 2!s bid and thus demonstrably suggest that bidding on over 2!s is worthwhile. The situation might be different if the partnership is playing weak jump shifts, as they might have been deciding between 2!s and, say, 3!d, with 6 diamonds and 3 spades.)
To my mind the Contents in the laws are far more important than the Index. In the 2007 laws, which was the first time they had an Index, the Contents were removed but fortunately they were returned for 2017. As Robin says though, things that are matters of regulation rather than law don't appear in the law book.