The Supreme Court granted certiorari in Diaz v. United States, No. 23-14 (cert. granted, Nov. 13, 2023).
Discussions and relevant cert. papers are available here: https://www.scotusblog.com/case-files/cases/diaz-v-united-states/
The petition for certiorari frames the “Question Presented” as follows:
Federal Rule of Evidence 704(b) provides: “In a criminual case, an expert witness must not state an opinion about whether the defendant did or did not have a mental state or condition that constitutes an element of the crime charged or of a defense. Those matters are for the trier of fact alone.” Fed.R.Evid.704(b).
The question is: In a prosecution for drug trafficking —— where an element of the offense is that the defendant knew she was carrying illegal drugs —— does Rule 704(b) permit a governmental expert witness to testify that most couriers know they are carrying drugs and that drug-trafficking organizations do not entrust large quantities of drugs to unknowing transporters?