California Code, Penal Code - PEN § 243.83

(1) Throw any object on or across the court or field of play with the intent to interfere with play or distract a player.

(2) Enter upon the court or field of play without permission from an authorized person any time after the authorized participants of play have entered the court or field to begin the sporting event and until the participants of play have completed the playing time of the sporting event.

(b)(1) The owner of the facility in which a professional sporting event is to be held shall provide a notice specifying the unlawful activity prohibited by this section and the punishment for engaging in that prohibited activity.

(2) The notice shall be prominently displayed throughout the facility or may be provided by some other manner, such as on a big screen or by a general public announcement.  In addition, notice shall be posted at all controlled entry areas of the sporting facility.

(3) Failure to provide the notice shall not be a defense to a violation of this section.

(1) “Player” includes any authorized participant of play, including, but not limited to, team members, referees however designated, and support staff, whether or not any of those persons receive compensation.

(2) “Professional sporting event” means a scheduled sporting event involving a professional sports team or organization or a professional athlete for which an admission fee is charged to the public.