In People v. Torres (1995) 33 Cal.App.4th 37, the witness, after providing the jury with definitions of robbery and extortion, testified that a robbery "is what happened in this particular case." ( Id. at p. 44.) The Torres court held a witness's testimony about the meaning of a statute was improper because it is the duty of the court, not a witness, to instruct on matters of law. The court also held that an opinion that the defendant was guilty of a crime or that a crime had been committed was improper, not because the testimony went to the ultimate issue of fact, but because such an opinion would not be helpful to the trier of fact. ( Id. at pp. 46-47.) The Court explained, "The reason for employing this rule that a witness cannot express an opinion concerning the guilt or innocence of the defendant is not because guilt is the 'ultimate issue of fact' to be decided by the jury. Opinion testimony often goes to the ultimate issue in the case. Rather, opinions on guilt or innocence are inadmissible because they are of no assistance to the trier of fact." ( Id. at p. 47.)