O.C.G.A. § 24-7-704: Ultimate issue opinion.

(a) Except as provided in subsection (b) of this Code section, testimony in the form of an opinion or inference otherwise admissible shall not be 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 an accused in a criminal proceeding shall state an opinion or inference as to whether the accused 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.