Rule 704 United States Federal Rules of Evidence
Rule 704 of the Federal Rules of Evidence is about Opinion on an Ultimate Issue. It is under Article VII (Opinions and Expert Testimony) of the Rules.
(a) In General — Not Automatically Objectionable. An opinion is not objectionable just because it embraces an ultimate issue.
(b) Exception. In 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.
