Look up some of the cases that the ACLU filed.
They were landmark cases concerning the rights of the mentally ill.
There were also many patients who were dropped off at these places and died there. Also note that some patients weren't even mentally ill but misdiagnosed.
There is a lot of material about this online.
Now do I think treatment is lacking? Absolutely.
The one man I feared while I worked at an E.R. was a schizophrenic patient. And what do you know, he ended up pulling a knife on the doctor one day.......they would hold this man for three days then release him due to laws. It wasn't enough. I still remember his whole name ..and this was 20years ago.
With all due respect, mental institutions were not prisons, they were hospitals. Because of illness, there are some human beings who should be separated from society in order to protect society. It has nothing to do with rights and everything to do with safety.
JMO