For clinical nursing procedures your policies can reference a widely accepted nursing textbook
, as dansamy noted in the post above.
However, your policies are going to need to reflect the mental health laws in your state and applicable laws/regulations of your local and state health departments and Joint Commission, if you are accredited by them. This also should not be done unilaterally by nursing alone -- you will need to work with your medical director, other disciplines who play a role in the patients' care, and whoever in your organization is responsible for regulatory compliance.
It will be a large undertaking; however, if the facility has already been cited for deficiencies, it MUST be a priority. Failure to correct previously cited items would likely have a negative effect on the facility and its management team, and that now includes you.