Cal. Penal Code § 914.1

When a grand jury is impaneled, for purposes which include the investigation of, or inquiry into, county matters of civil concern, the judge of the superior court of the county, in addition to other matters requiring action, shall call its attention to the provisions of Chapter 1 (commencing with Section 23000) of Division 1 of Title 3, and Sections 24054 and 26525 of the Government Code, and instruct it to ascertain by a careful and diligent investigation whether such provisions have been complied with, and to note the result of such investigation in its report. At such time the judge shall also inform and charge the grand jury especially as to its powers, duties, and responsibilities under Article 1 (commencing with Section 888) of Chapter 2, and Article 2 (commencing with Section 925), Article 3 (commencing with Section 934) of this chapter, Article 3 (commencing with Section 3060) of Chapter 7 of Division 4 of Title 1 of the Government Code, and Section 17006 of the Welfare and Institutions Code.