In U.S. v. Ramirez, No. 05-12765 (Feb. 1, 2007), the Court affirmed the denial of a motion to suppress, holding that the police did not detain Ramirez in violation of his Fourth Amendment rights.
Ramirez was pulled over for a traffic infraction. After police had determined that he had no outstanding warrants, and after they had issued him a citation and handed him back his papers, a police officer asked Ramirez if he was carrying anything illegal in the car. Ramirez consented to a search of his car, in which 7 kilos of cocaine were found.
Rejecting the argument that the police officer’s question constituted an unreasonable detention, the Court held that at this point the traffic stop had converted into a "consensual encounter." A reasonable person would have felt free to leave and to decline the request for more information.