What is the legal test for calling upon an expert in a medical malpractice case?

On the other hand, the witness typically called upon as an expert to give an opinion on the scientific procedure used in a particular criminal case is often a laboratory technician employed by a local law enforcement agency. " 'A person is qualified to testify as an expert if he has special knowledge, skill, experience, training, or education sufficient to qualify him as an expert on the subject to which his testimony relates.' (Evid.Code, 720, subd. (a).) The trial court is given considerable latitude in determining the qualifications of an expert and its ruling will not be disturbed on appeal unless a manifest abuse of discretion is shown. [Citations.]" (People v. Kelly, supra, 17 Cal.3d at p. 39, 130 Cal.Rptr. 144, 549 P.2d 1240.) Once the court acts within its discretion and finds the witness qualified, as it did in this case, the weight to be given the testimony is for the jury to decide.