In what circumstances will a court admit or deny testimony from a police officer that a defendant's shaking his head from side to side means that he had been asked if he had any more narcotics?

In People v. Hernandez (1977) 70 Cal.App.3d 271, 138 Cal.Rptr. 675 the court found an abuse of discretion by the trial court in admitting testimony regarding a police officer's opinion that defendant's shaking his head from side to side meant that he had been asked if he had any more narcotics and had responded that he did not. (Id. at pp. 274-275, 138 Cal.Rptr. 675.) The court held the officer's expertise did not add any probative value to the evidence, which the jury was quite capable of analyzing for itself. (Id.)