Does section 28 and 29 of the California Penal Code allow an expert to testify that the accused tends to overreact to stress and apprehension?

In People v. Nunn (1996) 50 Cal.App.4th 1357, 1364, the court examined the "dividing line between permissible opinion testimony concerning mental state and impermissible testimony concerning whether the defendant did or did not have the required mental state." It concluded that Penal Code sections 28 and 29 "allow the presentation of detailed expert testimony relevant to whether a defendant harbored a required mental state or intent at the time he acted." (Id. at p. 1365.) Thus, for example, an expert can testify that the accused tends to overreact to stress and apprehension as a

Page 10