In a criminal case, an expert may not state an opinion about whether the defendant had a mental state constituting an element of the crime. This prohibition is found in which rule?

In a criminal case, an expert may not state an opinion about whether the defendant had a mental state constituting an element of the crime. This prohibition is found in which rule?

• A. Rule 705
• B. Rule 802
• C. Rule 704(b)
• D. Rule 801

Answer: (C)

In criminal cases, there is a specific limit on what experts can say about the defendant’s mental state. Rule 704(b) bars an expert from giving an opinion about whether the defendant had the mental state that constitutes an element of the crime (for example, whether the defendant had intent or knowledge required for the offense). This keeps the determination of guilt as a jury function, avoiding an expert effectively deciding the mental state for the jury. Rule 704(a) allows experts to express opinions on ultimate issues in general, but 704(b) provides this explicit exception for mental-state conclusions tied to a criminal element—precisely the prohibition described. The other rules listed cover different topics (for example, Rule 802/801 deal with hearsay, and Rule 705 concerns the basis for an expert’s opinion), so they don’t address this specific restriction. So, the prohibition comes from Rule 704(b).

In criminal cases, there is a specific limit on what experts can say about the defendant’s mental state. Rule 704(b) bars an expert from giving an opinion about whether the defendant had the mental state that constitutes an element of the crime (for example, whether the defendant had intent or knowledge required for the offense). This keeps the determination of guilt as a jury function, avoiding an expert effectively deciding the mental state for the jury.

Rule 704(a) allows experts to express opinions on ultimate issues in general, but 704(b) provides this explicit exception for mental-state conclusions tied to a criminal element—precisely the prohibition described. The other rules listed cover different topics (for example, Rule 802/801 deal with hearsay, and Rule 705 concerns the basis for an expert’s opinion), so they don’t address this specific restriction.

So, the prohibition comes from Rule 704(b).