“Party” includes the agency that is taking action, the person to which the agency action is directed, and any other person named as a party or allowed to appear or intervene in the proceeding. If the agency that is taking action and the agency that is conducting the adjudicative proceeding are separate agencies, the agency that is taking action is a party and the agency that is conducting the adjudicative proceeding is not a party.
Source:
Section 11405.60, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=GOV§ionNum=11405.60..