Unfortunately not everyone in a group chat may be fully vetted, in which case they could be feds collecting "evidence". Some chats may have publicly circulating invite links.
But any judge that doesn't immediately reject such cases on a first-amendment basis is doing the business of an authoritarian dictator. This is fully protected speech and assembly.
> Unfortunately not everyone in a group chat may be fully vetted,
Curious how many group chats have unknowingly allowed a well known journalist into their groups.
> any judge that doesn't immediately reject such cases on a first-amendment basis
If you say something illegal in a chat with a cop in it, or say it in public, I don’t think there are Constitutional issues with the police using that as evidence. (If you didn’t say anything illegal, you have a valid defence.)