The justification for an inventory search does not rest on probable cause, and hence the absence of a warrant is immaterial to the reasonableness of the search. The Supreme Court has previously established that the inventory search constitutes a well-defined exception to the warrant requirement. See South Dakota v. Opperman, 428 U.S. 364 (1976). See also United States v. Chadwick, 433 U.S. 1 (1977), and Arkansas v. Sanders, 442 U.S. 753 (1979). In the former, the court noted that 'probable cause to search is irrelevant' in inventory searches and went on to state: 'This is so because the salutary functions of a warrant simply have no application in that context; the constitutional reasonableness of inventory searches must be determined on other bases.' 433 U.S., at 10, n. 5. See also United States v. Edwards, 415 U.S. 800 (1974).
In that case the court addressed Cooper v. California, 386 U.S. 58 (1967), where the Court sustained a warrantless search of an automobile that occurred a week after its owner had been arrested. It explained Cooper in the following manner: 'It was no answer to say that the police could have obtained a search warrant, for ...