Federal Rule of Evidence 704(b) provides that
No expert witness testifying with respect to the mental state or condition of a defendant in a criminal case may state an opinion or inference as to whether the defendant did or did not have the mental state or condition constituting an element of the crime charged or of a defense thereto. Such ultimate issues are matters for the trier of fact alone.
Does this rule prevent DEA agents from testifying that the quantities of drugs recovered from a defendant are consistent with intent to distribute? The answer is "no" according to the Sixth Circuit in its recent opinion in United States v. Alford, 2009 WL 1587267 (6th Cir. 2009), at least if the defendant does not object to such testimony.
From Prof. Colin Miller, 16 June 2009.