As the governing and policy-making body of the Department of Public Health (DPH), the Health Commission is given authority by the San Francisco Charter to oversee and, with the DPH, control the City and County hospitals, emergency medical services, and in general provide for the preservation, promotion, and protection of the physical and mental health of San Francisco residents, except where the Charter grants such authority to another City officer or Department. The Mayor appoints the seven Health Commissioners to four-year terms.