What is the legal test for the weight and effect of expert testimony in a criminal trial?

When expert testimony is received in a criminal trial, the trial court must instruct the jury sua sponte on the weight and effect of such testimony. ( 1127b¹¹; People v. Reeder (1976) 65 Cal.App.3d 235, 241.) Relevant here, CALCRIM No. 332 instructs the jury to consider "the expert's knowledge, skill, experience, training and education, the reasons the expert gave for any opinion, and the facts or information on which the expert relied in reaching that opinion." By contrast, CALCRIM No. 333 instructs the jury to evaluate lay witness opinion testimony, considering "the extent of the witness's opportunity to perceive the matters on which his or her opinion is based, the reasons the witness gave for any opinion, and the facts or information on which the witness relied in forming that opinion."

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