There is a legal process to put people who are mentally ill into institutions against their will.
in NYC & San Francisco we have completely feral nuts wandering around covered in their own feces. They are absolutely a menace to themselves and others.
Look at that Jared Loughner case, every body knew it was just a matter of time.
I had to risk arrest to stop a guy like that, he was threatening a girl I know - he was sure that cats have digital cameras in their eyes & that the pope was commanding him to slit her throat because ( he imagined ) she was in porn movies.
After I bonked him I almost got arrested except he started demanding that the cops let him into peoples apartments due to his papal passport, the cops knew he was nuts but didn't bring him to a hospital.
In NYC a few yrs ago a woman spent 5 yrs living on crap taken from a nearby garbage can & whatever people gave her, she was raped multiple times.
She spent her days imaging she was directing traffic, somehow someone intervened and she was hospitalized against her will, when she realized ( after medication )
what happened she was interviewed and wondered why no one ever helped her.
back in the early 80's they closed down a lot of mental hospitals & sent those poor unfortunates into the streets. It is cruel that they are dying in the street but there is no way to help them. they are ignored until they commit a crime then get incarcerated.
In NYC they often live on a subway platform, stinking so bad no one can stand near them, then one day they push someone in front of a train and kill them...then they get noticed.