On September 25, 2020, California Governor Gavin Newsom signed a law, Senate Bill (SB) 855, that defines behavioral health as a medical necessity for private health plans. Medical necessity determination criteria must be based on current generally accepted standards of mental health and substance use disorder care. Health care service plans and disability insurers are prohibited from limiting benefits or coverage for mental health and substance use disorders to short-term or acute treatment. Utilization review criteria must use the criteria and guidelines set forth in the most recent versions of treatment criteria developed by the non-profit professional association . . .