[Polixenes]

I was directing a local ACBL club game yesterday and was called to a table. After 1NT opening, next seat Doubled (Alerted). Double meant one of "Both red suits, both black suits, or a long club suit". Doubler's partner required to bid 2C if third seat passes. It's part of a modified Cappelletti. 2C overcall would have shown a single suiter (not clubs), 2D for majors, 2H for H+C, 2S for S+D and 2NT for minors.

The 3rd seat player called me and asked me if the opponents were required to provide a Written Defence. She was convinced they should. I had no idea. In the absence of knowledge I ruled that they did not need to write down a defence. I said they could raise the question to the bridge club management committee but I'm not sure what will happen at that point.

Out of my depth on this question and appreciate any guidance - how to deal with this next time, and how to help the management committee decide what to do when they come to ask me about it.

[hrothgar]

The rules wrt Written Defenses are defined in the ACBL Convention chart

Said rules read:

Pre-alerts and Written Defenses
Two classes of methods are particularly difficult to defend against, and these methods are allowed only in events governed by the Open+ Chart, and then only in segments of six boards or longer. These methods, based on #3 or #7 of the Opening Bids section of the Open+ Chart, require both a pre-alert and a written defense.
Official ACBL defenses must be provided when possible. In the event that a convention does not yet have an official ACBL defense, the pair must, before using it in an ACBL sanctioned game:
● Submit a full description of the convention and a proposed defense to the ACBL committee for approval. The defense must be provisionally approved. A method is “provisionally approved” if an acknowledgement receipt was sent by the ACBL upon submission and either: (a) the committee sends an email granting provisional approval; or (b) it was submitted at least 30 days before the ACBL sanctioned event in which it is used and the committee has not rejected it; and
● Provide the submitted defense to any opponents.
It is recommended that any new convention and written defense be posted online for public comment.
Note: For any method for which a written defense is required, the opposing pair may use their own defense rather than the one provided. The defending pair may refer to a pre-written copy of their own defense.

[PrecisionL]

A written defense for a NT defense is NOT required in ACBLand.

(1) Written defenses are required in competition of less than 6 boards for 1-bids that are artificial and not strong and shows length in a known suit other than the one opened (Open Chart and Open+ Chart), or

(2) Written defenses are required in competition of less than 6 boards for artificial pre-empts below 3NT that does not show at least one known suit (Open+ Chart)

[Polixenes]

My thanks to you both!

[paulg]

If an experienced pair were playing something unusual at our (non-ACBL) club and it was spoiling the enjoyment of our less experienced players, we'd just have a quiet word and say that it would be helpful if they could suggest that the opponents treat the double as a club suit until proved otherwise. It is not what the NBO regulations say but it would help maintain the friendly atmosphere at the club.

In our jurisdiction they would need to pre-alert this double, which would be a good time to let people know this aspect of the defence. When you are surprised by an uncommon convention, it is very easy to panic and not take on board the intricacies immediately, especially when less experienced.

On the other hand, I'd expect any tournament player to cope.