What is the legality of hospitals using restraints?

Each state has forms. That must be completed by the nurses & doctors at psychiatric inpatient & outpatient units, both public & private, for every incident that requires denial of patient rights or physical/chemical restraints. These are reviewed by the chief of the state's mental health/developmental services & by the mhds commission to insure that all other methods were tried first & that the action was appropriate.
Safety. It may be authorized in some situations for safety reasons. Each hospital has very specific instructions regarding use of restraints. You can ask this question on avvo. Com for a legal opinion.