Well, several questions, anyway.
I got to thinking of this when "The Drumhead" came into my mind. One of Admiral Satie's aides was a full Betazoid (Sabin Jenestra). Why didn't he read Simon Tarses' mind and be done with it? They were trying to figure out what Tarses was hiding, what he knew, etc. Is there some reason why Sabin didn't simply scan Tarses? He could already tell Tarses was hiding something. Why not follow through on it? Is there a law that says he can't?
I don't remember if the show ever said there was any kind of law or cultural taboo against a forcible mind scan. Do people who are being scanned know that they are?
I remember that Tarses had the right not to answer questions, but what about having his mind scanned? I don't remember if the episode ever dealt with that. I guess there would have to be some protection, otherwise it would never be possible to have any kind of privacy on Betazed or even when other Betazoids are around.
(OTOH, as ST VI showed, Spock was permitted to forcibly mind meld with Valeris to find out what *she* knew...so if a Vulcan can do it, why couldn't a Betazoid? Especially since Betazoids don't need to touch you to read your mind.)