A police officer received a radio call notifying him of a robbery of a clothing store. The report described the getaway car. Shortly thereafter, the officer spotted an automobile which he thought might be the getaway car. He and several other officers stopped the vehicle. The occupants of the automobile, Rakas (D) and two female companions (D1), were ordered out of the car. The officers then searched the interior of the vehicle. They discovered a box of rifle shells in the glove compartment, which had been locked, and a sawed-off rifle under the front passenger seat. After discovering the rifle and the shells, the officers took Ds to the station and placed them under arrest. D1 moved to suppress the rifle and shells seized from the car on the ground that the search violated the Fourth and Fourteenth Amendments. They conceded that they did not own the automobile and were simply passengers; D had been the driver of the vehicle at the time of the search. Nor did they assert that they owned the rifle or the shells seized. The trial court held that D1 lacked standing and denied the motion to suppress the evidence. The Appellate Court affirmed the trial court's denial of D1's motion to suppress because it held that 'without a proprietary or other similar interest in an automobile, a mere passenger therein lacks standing to challenge the legality of the search of the vehicle.' The Illinois Supreme Court denied petitioners leave to appeal. The Supreme Court granted certiorari.