Police violate the Fourth Amendment when they prolong a traffic stop beyond the time needed to handle the matter for which the stop was made in order to conduct a dog sniff. An officer pulled Rodriguez over for swerving his car onto the shoulder of the road then back into the lane. The officer ran a records check of Rodriguez and his passenger. After issuing Rodriguez a written warning, the officer asked if he would consent to a dog sniff of his car. Rodriquez refused. The officer ordered him out of the car and waited seven to eight minutes for another officer to arrive before conducting the dog sniff. The dog alerted and officers found a large bag of methamphetamine. Rodriquez was charged with intent to distribute. He moved to suppress the drug evidence on the basis that the officer had prolonged the traffic stop without reasonable suspicion in order to conduct the dog sniff. The district court denied the motion. The Eighth Circuit affirmed. The Supreme Court granted certiorari. Held: Vacated and remanded. The tolerable duration of a traffic stop is the amount of time necessary to address the traffic violation that warranted the stop and attend to related safety concerns. (Illinois v. Caballes (2005) 543 U.S. 405, 407.) Although a driver’s license check, a warrant check, and an inspection of the automobile’s proof of insurance and registration are related to traffic safety concerns, a dog sniff “is a measure aimed at detecting evidence of ordinary criminal wrongdoing.” It is not an ordinary part of a traffic stop. Additionally, dog sniffs that occur within a short time following completion of a traffic stop are not “de minimis” intrusions that may be justified by the government’s interest in detecting drug trafficking. An officer may only prolong a traffic stop to conduct unrelated checks, like a dog sniff, if there is reasonable suspicion to justify detaining the individual. The Court remanded so that the Eighth Circuit could consider whether the officer had reasonable suspicion to detain Rodriguez beyond the completion of the traffic infraction investigation.