Cal. Pen. Code § 312.1
In any prosecution for a violation of the provisions of this chapter or of Chapter 7.6 (commencing with Section 313), neither the prosecution nor the defense shall be required to introduce expert witness testimony concerning the obscene or harmful character of the matter or live conduct which is the subject of the prosecution. Any evidence which tends to establish contemporary community standards of appeal to prurient interest or of customary limits of candor in the description or representation of nudity, sex, or excretion, or which bears upon the question of significant literary, artistic, political, educational, or scientific value shall, subject to the provisions of the Evidence Code, be admissible when offered by either the prosecution or by the defense.
Ca. Pen. Code § 312.1