What does it mean if an Expert Witness is testifying about the Ultimate Issue?

When an expert witness testifies about the ultimate issue, they are providing their opinion on a key question that the jury or judge must decide in the case, such as the cause of an injury or the mental state of a defendant. This testimony can help clarify complex subjects for the court, but it may also raise concerns about the expert overstepping their role by making determinations that are typically reserved for the judge or jury. Ultimately, the admissibility of such testimony can depend on the jurisdiction and the specifics of the case.