Cal. Public Utilities Code § 2102

Whenever the commission is of the opinion that any public utility is failing or omitting or about to fail or omit, to do anything required of it by law, or by any order, decision, rule, direction, or requirement of the commission, or is doing anything or about to do anything, or permitting anything or about to permit anything to be done, in violation of law or of any order, decision, rule, direction, or requirement of the commission, it shall direct the attorney of the commission to commence an action or proceeding in the superior court in and for the county, or city and county, in which the cause or some part thereof arose, or in which the corporation complained of has its principal place of business, or in which the person complained of resides, for the purpose of having such violations or threatened violations stopped and prevented, either by mandamus or injunction. The attorney of the commission shall thereupon begin such action or proceeding in the name of the people of the State of California, by petition to such superior court, alleging the violation or threatened violation complained of, and praying for appropriate relief by way of mandamus or injunction.