Is a defendant's past criminal record admissible at trial?

Defendant now complains that the trial judge should, sua sponte, have instructed the jury to disregard the "prior conduct" evidence. We rejected a similar argument in the context of prior criminal offenses in People v. Collie, supra, 30 Cal.3d 43, 64, 177 Cal.Rptr. 458, 634 P.2d 534: "Neither precedent nor policy favors a rule that would saddle the trial court with the duty either to interrupt the testimony sua sponte to admonish the jury whenever a witness implicates the defendant in another offense, or to review the entire record at trial's end in search of such testimony. There may be an occasional extraordinary case in which unprotested evidence of past offenses is a dominant part of the evidence against the accused, and is both highly prejudicial and minimally relevant [45 Cal.3d 252] to any legitimate purpose.... But we hold that in this case, and in general, the trial court is under no duty to instruct sua sponte on the limited admissibility of evidence of past criminal conduct."