If his or her suspicions are confirmed, then there may be probable cause to either search the vehicle and/or arrest its occupant(s), depending on the nature of the suspected violations. In "Illinois v. Caballes", the Supreme Court held that a drug dog may sniff the exterior of a vehicle during a traffic stop so long as any delay in calling the dog to the scene does not unreasonably prolong the traffic stop. The use of a drug dog is "sui generis" and a dog's sniff is not considered a search in and of itself under the 4th Amendment.