§3602. Pleading and proof of truth as justification for defamation
Whenever any civil suit for slander, defamation, or for a libel, shall be instituted in any court of this state, it shall be lawful for the defendant to plead in justification the truth of the slanderous, defamatory or libelous words or matter, for the uttering or publishing of which he may be sued; and in the trial of the issue in such suit, to maintain and prove his plea by all legal evidence.