Appellant was arrested for driving under the influence. Officers searched his vehicle, finding methamphetamine and drug paraphernalia in a backpack in the trunk. Appellant filed a motion to suppress, pursuant to Penal Code section 1538.5. The prosecution argued that the search was a lawful inventory search. The court denied his motion. Subsequently, appellant filed a supplemental 1538.5 motion, arguing that the issue of the inventory search was not fully litigated in the previous hearing, and that the inventory search was unlawful because it was not conducted pursuant to an existing policy or established routine. The trial court concluded it had no jurisdiction to hear a supplemental motion. Here, the appellate court reversed. An inventory search is lawful where it follows established standardized procedures. Here, once the prosecution claimed that an inventory search was justified, it was required to prove the existence of a standardized procedure for it. Therefore, appellant was entitled to fully litigate this issue, and remand was required.