California Code, Penal Code - PEN § 626.6

(a) If a person who is not a student, officer, or employee of a college, or university, or an independent institution of higher education, and who is not required by their employment to be on the campus or any other facility owned, operated, or controlled by the governing board of that college, university, or an independent institution of higher education enters a campus or facility, and it reasonably appears to the chief administrative officer of the campus or facility, or to an officer or employee designated by the chief administrative officer to maintain order on the campus or facility, that the person is committing any act likely to interfere with the peaceful conduct of the activities of the campus or facility, or has entered the campus or facility for the purpose of committing any such act, the chief administrative officer or their designee may direct the person to leave the campus or facility.  If that person fails to do so or if the person willfully and knowingly reenters upon the campus or facility within seven days after being directed to leave, the person is guilty of a misdemeanor and shall be punished by a fine not exceeding five hundred dollars ($500), by imprisonment in a county jail for a period of not more than six months, or by both that fine and imprisonment.

(b) The provisions of this section shall not be utilized to impinge upon the lawful exercise of constitutionally protected rights of freedom of speech or assembly.

(c) When a person is directed to leave pursuant to subdivision (a), the individual directing the person to leave shall inform the person that if the person reenters the campus or facility within seven days the person will be guilty of a crime.