In what circumstances will a court allow a police expert to testify in a criminal case?

This distinction exists in California law as well. In People v. Harvey (1991) 233 Cal.App.3d 1206, 285 Cal.Rptr. 158, upon which respondent relies, a police expert was permitted to testify in detail concerning the organization and methods employed by Colombian cocaine rings. He then testified as to the meaning of evidence in the case against the backdrop of the organizational structure and methodology. (Id. at pp. 1216-1217, 285 Cal.Rptr. 158.)

The court held that permitting this expert testimony was not error. When "the subject matter [of the expert testimony] was sufficiently beyond the common expertise of the trier of fact to render expert testimony not only helpful but necessary for an understanding of the meaning and import of various actions" established by other evidence, it is within the trial court's discretion to permit such testimony. (People v. Harvey, supra, 233 Cal.App.3d at p. 1228, 285 Cal.Rptr. 158.)