California Code, Family Code - FAM § 9001

(a) Except as provided in Section 9000.5, before granting or denying a stepparent adoption request, the court shall review and consider a written investigative report.  The report in a stepparent adoption case shall not require a home study unless so ordered by the court upon request of an investigator or interested person, or on the court's own motion.  “Home study” as used in this section means a physical investigation of the premises where the child is residing.

(b) At the time of filing the adoption request, the petitioner shall inform the court in writing if the petitioner is electing to have the investigation and written report completed by a licensed clinical social worker, a licensed marriage and family therapist, a licensed professional clinical counselor, or a private licensed adoption agency, in which cases the petitioner shall not be required to pay an investigation fee pursuant to Section 9002 at the time of filing, but shall pay these fees directly to the investigator.  Absent that notification, the court may, at the time of filing, collect an investigation fee pursuant to Section 9002, and may assign one of the following to complete the investigation:  a probation officer, a qualified court investigator, or the county welfare department, if so authorized by the board of supervisors of the county where the action is pending.

(c) If a private licensed adoption agency conducts the investigation, it shall assign the investigation to a licensed clinical social worker, licensed professional clinical counselor, or licensed marriage and family therapist associated with the agency.  A grievance regarding the investigation shall be directed to the licensing authority of the clinical social worker, licensed professional clinical counselor, or marriage and family therapist, as applicable.

(d) This section does not require the State Department of Social Services to issue regulations for stepparent adoptions.