California Code, Penal Code - PEN § 243.8

(a) When a battery is committed against a sports official immediately prior to, during, or immediately following an interscholastic, intercollegiate, or any other organized amateur or professional athletic contest in which the sports official is participating, and the person who commits the offense knows or reasonably should know that the victim is engaged in the performance of his or her duties, the offense shall be punishable by a fine not exceeding two thousand dollars ($2,000), or by imprisonment in the county jail not exceeding one year, or by both that fine and imprisonment.

(b) For purposes of this section, “sports official” means any individual who serves as a referee, umpire, linesman, or who serves in a similar capacity but may be known by a different title or name and is duly registered by, or a member of, a local, state, regional, or national organization engaged in part in providing education and training to sports officials.