Federal Rule of Evidence 704(b) states, "[i]n a criminal 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."

The question presented is whether the government may circumvent Federal Rule of Evidence 704(b) by eliciting an expert opinion on the mental state of a "hypothetical" person whose circumstances – including the receipt of a specific, unique text message – are a carbon copy of the defendant's, thereby having the expert functionally opine on the defendant's mental state.

Whether the government may circumvent Federal Rule of Evidence 704(b) by eliciting expert opinion on a hypothetical person's mental state that mirrors the defendant's circumstances, thereby functionally opining on the defendant's mental state or condition that constitutes an element of the crime charged