Premature Dummy
The contract is 4S by South, and North has a really useful void.
West put out an opening lead face down, and North spreads his hand and says "look - lots of ruffing potential". Oops.
But...
The opening lead has not yet been faced, so North is not yet dummy (per the definitions).
What law, if any, has North transgressed?
Comments
Well, either North is dummy and is communicating about the play to declarer, or North is communicating during the auction. This is the kind of remark which doesn't really convery anything specific and would generally be shrugged off by the players but is nonetheless faintly problematic, at least worthy of a caution.
I think there's probably only going to be an issue if the auction is reopened (e.g. due to misinformation), in which case South has unauthorised information, and if N/S end up on defence they have 13 penalty cards. If play starts with South as declarer, I doubt there's been any damage (unless North has hinted a line of play to South, which again is unlikely to cause damage unless the ruffing potential is clear to North but not South).