Affirming a conviction for importation of cocaine and possession with intent to distribute, the 9th Circuit panel wrote that neither United States v.Vallejo, 237 F.3d 1008 (9th Cir. 2001), nor its progeny supports the establishment of a per se rule that expert testimony regarding the operation and structure of drug trafficking organizations or the modus operandi of couriers involved in drug trafficking organizations is inadmissible. The panel likewise declined the defendant's invitation to create a rule that an expert's testimony that a drug trafficking operation is unlikely to use an unknown courier is per se inadmissible in a non-complex case. The panel wrote that a district court's rulings in this area are considered on a case-by-case basis, not pursuant to per se rules.
