Trance is a natural state that can happen outside of mind control, and outside of the control/knowledge of the user.
So it should not be "illegal" by itself.
Consequences could be judged, and sanctions could be adjusted (for better or worst) taking in account the causes of course, including pushing part or totality of the blame on someone else.
I doubt that's the answer you were after, but I have no idea if you were after a quote or a reference I don't know or can't think of.