There is a activist/vigilantly group called Creep Catchers who pretend to be underage children selling sex. Then when a pedophile agrees to meet in person, they show up with video cameras, broadcast it live, and basically get the person to admit he's a pedophile.
Recently there was a case where they did this to a disabled man and had initially pretended the girl was of age, but I don't want to discuss morality.
It's my understanding that it's illegal to slander a person on a very public scale and that public humiliation isn't allowed. By the Creep Catchers own description, their job is to publicly humiliate pedophiles using the internet (but I would suspect a lot of the tactics would count as entrapment). When is this sort of activity illegal?
There was another case where they knocked on a door and when the person answered they started aggressively accusing her of being a pedophile and broadcasted it. Whether or not it was true, she denied that she was and said someone else was pretending to be her online. Is this allowed?