I truly don't understand the world you inhabit. A prior history of repeated attempts to commit harm are a pretty good predictor of future actions absent a compelling narrative suggesting otherwise.
Ex. Patient A was doing foo harmful behavior until we changed their medication and the devil stopped appearing in their dreams to give them orders.
Patient B had a history of trying to bite nurses noses off but has been well behaved for 2 years now and participating in therapy.
Every first world nation has standards and procedures for detaining people who are unwell and a danger to themselves and others. It usually involves "expert" opinion and bad behavior to get into such a situation and "expert" opinion to get out. There is an entire history of bad behavior and bad science involved here but the substitute for bad science is better science not let people get away with infinite malfeasance because they are nuts.
People are for example sometimes ordered to facilities where they may receive treatment in place of detention in prison or be taken into custody in the process of some bad behavior and be subjected to an evaluation based on their behavior.
What do you suggest we do with the guy trying to throw women into traffic when he is inevitably declared crazy? Dismiss the charges and let him go? Would you rather
-- He get the treatment he so clearly needs.
-- Someone get murdered by him.
-- The citizenry take matters into their own hands and rid themselves of him.
Option A is surely infinity preferable.