Neither the defendant nor the prosecuting attorney is required to disclose any materials or information which are work product as defined in subdivision (a) of Section 2018.030 of the Code of Civil Procedure, or which are privileged pursuant to an express statutory provision, or are privileged as provided by the Constitution of the United States.
Source:
Section 1054.6, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=PEN§ionNum=1054.6..