What is the test for habeas corpus?

While all intendments traditionally favor a new trial order, habeas corpus is a separate, collateral proceeding that attacks a presumptively valid judgment. "For purposes of collateral attack, all presumptions favor the truth, accuracy and fairness of the conviction and sentence; defendant thus must undertake the burden of overturning them. Society's interest in the finality of criminal proceedings so demands. . . . [Citations.]" (People v. Gonzalez (1990) 51 Cal.3d 1179, 1260, 275 Cal. Rptr. 729, 800 P.2d 1159, first italics added.)¹¹ This presumption against the validity of a collateral attack on a conviction and sentence weigh strongly toward close appellate review of all mixed law and fact determinations leading to a lower court's decision to grant relief on habeas corpus.¹²