Almost all US case law has held that any jurisdiction can make anything illegal unless there's a specific higher-ranking (state or federal) law protecting that act from being made illegal.
> Please read this Order carefully. Violation of or failure to comply with this Order is a misdemeanor punishable by fine, imprisonment, or both. (California Health and Safety Code § 120295, et seq.; Cal. Penal Code §§ 69, 148(a)(1))
> UNDER THE AUTHORITY OF CALIFORNIA HEALTH AND SAFETY CODE SECTIONS 101040, 101085, AND 120175, THE HEALTH OFFICER OF THE COUNTY OF ALAMEDA (“HEALTH OFFICER”) ORDERS: