SCOTUS granted cert today in Diaz v. United States, a case dealing with FRE 704(b), the rule prohibiting experts from testifying that a criminal defendant acted with the requisite mental state. The defendant in a drug case offered an "blind mule" defense (he did not realize he was carrying drugs); the prosecution rebutted with xpert testimony that drug dealers do not "typically" trust large amounts of drugs to unknown couriers, so in most circumstances a driver carrying the amount of drugs as Diaz knew he was transporting drug
The court should resolve a circuit split as to the scope of FRE 704(b)--whether it only prohibits expert opinion as to this defendant's mental state ("Diaz knew he was carrying drugs") or whether it also prohibits expert opinion about a general group of people that includes the defendant by obvious implication ("anyone carrying as much as Diaz was carrying knew he was carrying").
The Court will schedule the argument for later in the Term. Note this is the first pure FRE case the Court has taken in several years.
