What is the test for determining whether a witness was an accomplice?

The trial court has a duty to instruct the jury, sua sponte, to determine whether a witness was an accomplice in the charged offense, "'"whenever the testimony given upon the trial is sufficient to warrant the conclusion upon the part of the jury that a witness implicating a defendant was an accomplice."'" (People v. Snyder (2003) 112 Cal.App.4th 1200, 1218.) The pattern jury instruction to be given when the accomplice status of a witness is in dispute is CALCRIM No. 334 [Accomplice Testimony Must Be Corroborated: Dispute Whether Witness Is Accomplice]. Alternatively, if the evidence establishes as a matter of law that a witness was an accomplice, the jury must be so instructed, and the applicable jury instruction is CALCRIM No. 335 [Accomplice Testimony: No Dispute Whether Witness Is Accomplice]. (People v. Zapien (1993) 4 Cal.4th 929, 982.) In either event, the trial court must also instruct the jury, sua sponte, "'(1) that the testimony of the accomplice witness is to be viewed with distrust [citations], and (2) that the defendant cannot be convicted on the basis of the accomplice's testimony unless it is corroborated....' [Citation.]" (Ibid.)

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