The Court had to contrast the "automobile exception" with long standing court decisions which held that portable containers such as suitcases, despite their mobility, are not subject to the same warrantless search as automobiles. The rationale for this is that suitcases and the like are not nearly as mobile as an automobile, and detaining a container while awaiting a warrant is practical. Furthermore, containers are presumed to have a much higher expectation of privacy than vehicles, since their primary purpose is to transport belongings, and most are opaque (some are even locked), which suggests that the owner of a container generally does not expect the contents to be visible or accessible to others.