Cal. Penal Code § 633.5

Sections 631, 632, 632.5, 632.6, and 632.7 do not prohibit 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, including, but not limited to, human trafficking, as defined in Section 236.1, or a violation of Section 653m, or domestic violence as defined in Section 13700. Sections 631, 632, 632.5, 632.6, and 632.7 do not render any evidence so obtained inadmissible in a prosecution for extortion, kidnapping, bribery, any felony involving violence against the person, including, but not limited to, human trafficking, as defined in Section 236.1, a violation of Section 653m, or domestic violence as defined in Section 13700, or any crime in connection therewith.