What is the test for a court of last resort interpretation of the California Declaration of Rights?

7 " '(I)n the area of fundamental civil liberties which includes . . . all protections of the California Declaration of Rights we sit as a court of last resort, subject only to the qualification that our interpretations may not restrict the guarantees accorded the national citizenry under the federal charter. In such constitutional adjudication, our first referent is California law and the full panoply of rights Californians have come to expect as their due. . . .' " (Serrano v. Priest (1976) 18 Cal.3d 728, 764, 135 Cal.Rptr. 345, 366, 557 P.2d 929, 950; quoting from People v. Longwill (1975) 14 Cal.3d 943, 951 fn. 4, 123 Cal.Rptr. 297, 538 P.2d 753; see also other cases and authorities there cited.)