Also, I like the idea of having the Betazoid in that court - it's such an obvious idea that it deserves to be brought up, even if it isn't actually explored much.
TOS technology supposedly already included efficient lie detectors, and indeed no court session seemed to feature witnesses or accused actually lying to the court. Janice Lester managed to maneuver through a hearing on a completely untruthful basis, sure, but she wasn't the one being accused or heard as a witness - she could easily have avoided being subject to lie detection.
Did this technology go away by the time of TNG? We don't hear lies in the court, now do we? Instead, we fail to hear truths when people decide to hide them. The "psychotricorder" tech might still be there, as a triviality that can be utilized whenever the court suspects a lie, but things seldom come to that; if the tech indeed exists, courts might assume nobody bothers to lie in a way that would be caught. Fooling the machines by half-truths would always have been an option in TOS already, I guess.
However, a Betazoid half as good as Lwaxana Troi should be able to do much more than such a lie detector. Which may be why Betazoids that good are banned from using their abilities in court, and only those with abilities akin to Deanna Troi's are accepted. TOS already speaks of quantitative establishing of paranormal abilities, and there may exist reliable "ratings" for Betazoids that are referenced in basic humanoid rights so that the "thought police" concept can be avoided.
However, the accused cannot really know the rating of the Betazoid staring at him or her! Thus, use of one would be an effective psychological threat, and one that Satie could probably get away with, by the letter of the law, even if she violated its spirit...
Timo Saloniemi