Placing any burden at all on the defense, however slight, can be a “game changer” because such a burden requires uncertain or undecided jurors to side with the prosecution instead of the defense. In other words, when the fact finder is uncertain the unburdened party “‘must win.'[Citation.]” (People v. Jackson (2014) 58 Cal. 4th 724, 793-94, Liu, J., conc. and dis. opn; see also Medtronic, Inc. v. Mirowski Family Ventures, LLC (2014) 134 S. Ct. 843, 849-50 [patentee who has burden of proof would lose an infringement action if “the evidence being inconclusive, he failed to prove infringement.”].) Thus for example, “an error cannot be found harmless under Chapman when a reviewing court is not convinced but is genuinely unsure that there is a reasonable possibility that the error affected the verdict. The burden is on the state, not the defendant, to dispel the uncertainty.” (People v. Jackson, supra, 58 Cal. 4th at 793-94, Liu, J., conc. and dis. opn.).
Obviously, in a closely balanced case “‘the allocation of the burden of [proof] … can be outcome determinative …. [Citations.]’”(People v. Jackson, supra, 58 Cal. 4th at p. 793, quoting Gamache, 562 U.S. 1083, 1084, 131 S.Ct. 591, 593 (statement of Sotomayor, J; see also People v. Thomas (2013) 218 Cal.App. 4th 630, 646 [judgement reversed because reviewing court could not be certain the error was harmless]; Foxworth v. St. Amand (1st Cir. 2009) 570 F.3d 414, 436[ If the habeas court is uncertain whether the state has met its burden to show an error was harmless “the petitioner must win.” (internal citations and punctuation omitted)]; Farr v. County of Nevada (2010) 187 Cal.App. 4th 669, 682 [“Equal probability … does not satisfy a burden of proof.[citation]”].)
It follows that, in a criminal case, the jurors must understand that a juror must vote not guilty if he or she is “on the fence” – i.e., unsure or uncertain – that the prosecution has proved any element of the charge.