United States v. Medina-Copete, – F.3d – , 2014 WL 2958593 (10th Cir. July 2, 2014) 

The Tenth Circuit addressed an issue of first impression in this circuit: whether an expert witness may offer expert opinion testimony under rule 702 of the Federal Rules of Evidence about the connection between so-called “narco saint” iconography and drug trafficking. The district court had allowed a government expert to offer opinion testimony about the connection between veneration of Santa Muerte and drug trafficking. The Tenth Circuit held that the district court abused its discretion in allowing this testimony. First, the district court failed to consider whether a prayer constitutes a “tool of the trade,” as the Tenth Circuit has used that phrase. Second, it allowed the expert to testify based on his experience without considering the relevance and breadth of that experience, thereby ignoring the “facts or data” requirements of rule 702. Finally, the district court failed to consider the manner in which the expert’s techniques and methodology led to his opinions, instead relying on other courts’ treatment of similar testimony in different contexts. Given the significance of the expert’s opinions to the government’s case, the Tenth Circuit held that the erroneous admission of the expert’s opinion testimony regarding Santa Muerte was not harmless.