CA Gov't Code Section 13995.90

In any civil or criminal action or proceeding for violation of any of the following, proof that the act that is complained of was done in compliance with the provisions of this chapter is a complete defense to the action or proceeding:

(a)

The Cartwright Act, Chapter 2 (commencing with Section 16700) of Part 2 of Division 7 of the Business and Professions Code.

(b)

The Unfair Practices Act, Chapter 4 (commencing with Section 17000) of Part 2 of Division 7 of the Business and Professions Code.

(c)

Any rule of statutory or common law against monopolies or combinations in restraint of trade.