A jury's determination of criminal guilt or innocence is its exclusive responsibility. State v. Simon, 79 N.J. 191 (1979). A jury's verdict of ultimate criminal liability can never be equated simply with its determination of underlying facts; the determination of guilt or innocence transcends the facts on which it is based, no matter how compelling or inexorable those facts may be. State v. Ragland, 105 N.J. 189 (1986). The determination of facts that serve to establish guilt or innocence is a function reserved exclusively to the jury. State v. Collier, 90 N.J. 117 (1982). Hence, an expert's testimony that expresses a direct opinion that defendant is guilty of the crime charged is wholly improper. See, e.g., State v. Landeros, 20 N.J. 69, 74 (1955) (improper for expert, when asked if the defendant was guilty, to reply, 'He is as guilty as Mrs. Murphy's pet pig.'); see also Shutka v. Pennsylvania R.R. Co., 74 N.J.Super. 381, 401-02 (App.Div.1962) (court allowed expert opinion regarding the ultimate issue, noting, however, that expert testimony that expressed 'his belief as to how the case should be decided' would be improper).
A witness is not permitted to ...