Manuel Flores-Montano (defendant) was attempting to cross the United States border through the Otay Mesa Port of Entry in California when a customs official inspected his vehicle. The inspector took Flores-Montano’s car to a secondary inspection station. The gas tank sounded solid when tapped, so the inspector called a mechanic to remove the tank. The inspector found 37 kilograms of marijuana in the tank. The entire process took approximately one hour. Flores-Montano was indicted by a grand jury for the Southern District of California for importing and possessing marijuana with intent to distribute in violation of 21 U.S.C. §§ 952, 841(a)(1). Flores-Montano moved to suppress the evidence found in the gas tank. The district court granted the motion because the government did not have reasonable suspicion for the search. The Court of Appeals for the Ninth Circuit Affirmed. The United States Supreme Court granted certiorari.