The doctrine of collateral estoppel does not apply to bar retrial of a criminal prosecution predicated on the same offense which a trial court found was not proven for purposes of a probation revocation. Appellant was on probation when he was charged in a new case with possession of a firearm by a felon and with a probation violation based on the same offense. A jury trial resulted in a hung jury, so the court declined to revoke probation. A second jury then convicted appellant. Appellant argued the doctrine of collateral estoppel barred retrial based on the court’s ruling on the probation revocation. The court rejected the argument. The threshold requirements for collateral estoppel are: “1) the issue to be precluded must be identical to that decided in the prior proceeding; 2) the issue must have been actually litigated at that time; 3) the issue must have been necessarily decided; 4) the decision in the prior proceeding must be final and on the merits; and 5) the party against whom preclusion is sought must be in privity with the party to the former proceeding.” (People v. Garcia (2006) 39 Cal.4th 1070, 1077.) Usually, if these requirements are met, collateral estoppel bars relitigation of an issue decided in an early proceeding. These requirements are arguably satisfied in this case. However, there is a public-policy exception to the doctrine requiring courts to consider judicial economy, preservation of the integrity of the system, and protecting litigants from vexatious litigation. (See Lucido v. Superior Court (1990) 51 Cal.3d 335.) Here, the public-policy exception controls. Probation revocation hearings and trials have different purposes and interests (continued leniency towards a defendant vs. a new determination of guilt). So applying the exception preserves the integrity of the system. And a defendant is not subjected to vexatious litigation by being subjected to both a revocation hearing and a new trial. (Lucido, supra, 51 Cal.3d at p. 351.) The second trial was not barred.