What is the test for unanimous verdict in a criminal case?

A criminal defendant has a constitutional right to a unanimous jury verdict, meaning, "the jury must agree unanimously the defendant is guilty of a specific crime." (People v. Russo (2001) 25 Cal.4th 1124, 1131.) Thus, "if one criminal act is charged, but the evidence tends to show the commission of more than one such act, 'either the prosecution must elect the specific act relied upon to prove the charge to the jury, or the court must instruct the jury that it must unanimously agree that the defendant committed the same specific criminal act.' [Citation.]" (People v. Napoles (2002) 104 Cal.App.4th 108, 114.) In such a case, where no election has been made by the prosecution, the trial court possesses a sua sponte duty to provide a unanimity instruction. (People v. Dieguez (2001) 89 Cal.App.4th 266, 274-275.)

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"On the other hand, where the evidence shows only a single discrete crime but leaves room for disagreement as to exactly how that crime was committed or what the defendant's precise role was, the jury need not unanimously agree on the basis or, as the cases often put it, the 'theory' whereby the defendant is guilty. [Citation.] The crime of burglary provides a good illustration of the difference between discrete crimes, which require a unanimity instruction, and theories of the case, which do not. Burglary requires an entry with a specified intent. [Citation.] If the evidence showed two different entries with burglarious intent, for example, one of a house on Elm Street on Tuesday and another of a house on Maple Street on Wednesday, the jury would have to unanimously find the defendant guilty of at least one of those acts. If, however, the evidence showed a single entry, but possible uncertainty as to the exact burglarious intent, that uncertainty would involve only the theory of the case and not require the unanimity instruction. [Citation.] Other typical examples include the rule that, to convict a defendant of first degree murder, the jury must unanimously agree on guilt of a specific murder but need not agree on a theory of premeditation or felony murder [citation], and the rule that the jury need not agree on whether the defendant was guilty as the direct perpetrator or as an aider and abettor as long as it agreed on a specific crime [citation]." (People v. Russo, supra, 25 Cal.4th at pp. 1132-1133.)

Moreover, even where there are two distinct crimes, the trial court need not give a unanimity instruction where there is no evidence from which the jury could find the defendant guilty of one of the crimes but not both, for example where "[t]he parties never distinguished between the two acts" and "[t]he defense was the same as to both." (People v. Riel (2000) 22 Cal.4th 1153, 1199 [assuming two distinct acts of robbery, no error in failing to instruct on unanimity where the parties did not distinguish between them and the defendant's defense was that he was asleep at the time and did not commit any act of robbery].)

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