California Code, Civil Code - CIV § 48.8

(a) A communication by any person to a school principal, or a communication by a student attending the school to the student's teacher or to a school counselor or school nurse and any report of that communication to the school principal, stating that a specific student or other specified person has made a threat to commit violence or potential violence on the school grounds involving the use of a firearm or other deadly or dangerous weapon, is a communication on a matter of public concern and is subject to liability in defamation only upon a showing by clear and convincing evidence that the communication or report was made with knowledge of its falsity or with reckless disregard for the truth or falsity of the communication.  Where punitive damages are alleged, the provisions of Section 3294 shall also apply.

(b) As used in this section, “school” means a public or private school providing instruction in kindergarten or grades 1 to 12, inclusive.