Cal. Penal Code § 633.5

Nothing in Section 631, 632, 632.5, 632.6, or 632.7 prohibits one party to a confidential communication from recording the communication for the purpose of obtaining evidence reasonably believed to relate to the commission by another party to the communication of the crime of extortion, kidnapping, bribery, any felony involving violence against the person, or a violation of Section 653m. Nothing in Section 631, 632, 632.5, 632.6, or 632.7 renders any evidence so obtained inadmissible in a prosecution for extortion, kidnapping, bribery, any felony involving violence against the person, a violation of Section 653m, or any crime in connection therewith.