What is the test for obtaining a writ of habeas corpus against a plaintiff who was denied a petit jury?

The superior court, in issuing the writ of habeas corpus, concluded that petitioner was denied her constitutional right to a petit jury composed of "a representative and fair ethnic community cross-section so as to avoid a disproportionately small number of black prospective or potential jurors in proportion to the total number of available prospective or potential black jurors in the community [Duren v. Missouri (1979) 439 US 357, 99 S.Ct. 664, 58 L.Ed.2d 579; Taylor v. Louisiana (1975) 419 US , 95 S.Ct. 692, 42 L.Ed.2d 690; California Code of Civil Procedure Section 206]...."