Rule 704.        Opinion on Ultimate Issue

(a) Except as provided in subdivision (b), testimony in the

form of an opinion or inference otherwise admissible is not

objectionable because it embraces an ultimate issue to be

decided by the trier of fact. 

(b) No expert witness testifying with respect to the mental

state or condition of a defendant in a criminal case may state

an opinion or inference as to whether the defendant did or

did not have the mental state or condition constituting an

element of the crime charged or of a defense thereto.  Such

ultimate issues are matters for the trier of fact alone.