California Code, Business and Professions Code - BPC § 16758

In any action or proceeding brought by the Attorney General or any district attorney for the violation of this chapter no person shall be excused from attending, testifying or producing books, papers, or documents in obedience to subpena or under order of court on the ground that the testimony or evidence required of him may tend to incriminate him or subject him to any penalty.

No individual shall be prosecuted or subjected to any penalty for or on account of any transaction, matter or thing concerning which he may so testify or produce evidence in any action or proceeding brought by the Attorney General or a district attorney under this chapter.