What is The Law on Accomplice Testimony? California Penal Code Section 1111 provides: "A conviction can not be had upon the testimony of an accomplice unless it be corroborated by such other evidence as shall tend to connect the defendant with the commission of the offense; and the corroboration is not sufficient if it merely shows the commission of the offense or the circumstances thereof. An accomplice is hereby defined as one who is liable to prosecution for the identical offense charged against the defendant on trial in the cause in which the testimony of the accomplice is given." An "accomplice" is defined in that section as "one who is liable to prosecution for the identical offense charged against the defendant on trial in the cause in which the testimony of the accomplice is given." (Pen. Code, 1111.) This provision "serves to ensure that a defendant will not be convicted solely upon the testimony of an accomplice because an accomplice is likely to have self-serving motives." (People v. Davis (2005) 36 Cal.4th 510, 547.) In order to be charged with the identical offense, the witness must be a principal in the crime the defendant is charged with committing. (People v. Horton (1995) 11 Cal.4th 1068, 1113-1114.) "Principals" include "all persons concerned in the commission of a crime . . . whether they directly commit the act constituting the offense, or aid and abet in its commission, or, not being present, have advised and encouraged its commission . . . ." (Pen. Code, 31.) 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 , and (2) that the defendant cannot be convicted on the basis of the accomplice's testimony unless it is corroborated . . . .'" (Ibid., quoting People v. Gordon (1973) 10 Cal.3d 460, 466, fn. 3.) "Nonetheless, 'the failure to instruct on accomplice testimony pursuant to Penal Code, section 1111 is harmless where there is sufficient corroborating evidence in the record. The requisite corroboration may be established entirely by circumstantial evidence. Such evidence "may be slight and entitled to little consideration when standing alone. "' 'Corroborating evidence "must tend to implicate the defendant and therefore must relate to some act or fact which is an element of the crime but it is not necessary that the corroborative evidence be sufficient in itself to establish every element of the offense charged." ' " (People v. Zapien, supra, 4 Cal.4th at p. 982.) The corroborating evidence must also be independent of the accomplice's testimony. (People v. Avila, supra, 38 Cal.4th at p. 562.) To be chargeable with an identical offense, a witness must be considered a principal under section 31. (People v. Horton (1995) 11 Cal.4th 1068, 1113-1114.) Under that section "principals" include "all persons concerned in the commission of a crime, . . . whether they directly commit the act constituting the offense, or aid and abet in its commission . . . ." ( 31.) A mere accessory is not an accomplice. (People v. Horton, supra, at p. 1114.) An accomplice must have "'guilty knowledge and intent with regard to the commission of the crime.'" (People v. Hoover (1974) 12 Cal.3d 875, 879.) An aider and abettor is guilty not only of the intended crime, but also any other offense that is the natural and probable consequence of the intended offense. (People v. McCoy (2001) 25 Cal.4th 1111, 1117.) "Whether a person is an accomplice is a question of fact for the jury unless the facts and the inferences to be drawn therefrom are undisputed. " (People v. Coffman and Marlow (2004) 34 Cal.4th 1, 103.) "Factors to be considered by the trier of fact in determining 'whether one is an aider and abettor include presence at the scene of the crime, failure to take steps to attempt to prevent the commission of the crime, companionship, flight, and conduct before and after the crime.' " (People v. Garcia (2008) 168 Cal.App.4th 261, 273.) The failure to instruct based on section 1111 is an error of state law, subject to the reasonable probability standard of harmless error under People v. Watson (1956) 46 Cal.2d 818, 836-837. (People v. Whisenhunt (2008) 44 Cal.4th 174, 214.) The failure to give an instruction on accomplice testimony is harmless where the witness's testimony was sufficiently corroborated. (People v. Zapien (1993) 4 Cal.4th 929, 982.) "Corroborating evidence may be slight, may be entirely circumstantial, and need not be sufficient to establish every element of the charged offense." (People v. Hayes (1999) 21 Cal.4th 1211, 1271.) Corroborating evidence "is sufficient if it tends to connect the defendant with the crime in such a way as to satisfy the jury that the accomplice is telling the truth." (People v. Fauber (1992) 2 Cal.4th 792, 834.)