Expert witness jury instructions in California are outlined in the Judicial Council of California Civil Jury Instructions, Rule 219. Ca. Civ. Jury Inst. 219 (2017). This rule provides for the court to instruct the jury that experts can state opinions regarding their areas of expertise. Id. Also, the rule alerts the jury that it does not have to accept a witness’s testimony, and it does not have to use the testimony to come to a conclusion. Id. Additionally, the jury can use all or a portion of the expert’s testimony and should consider three things when deciding whether to rely on the expert’s testimony. Id. The three things to consider are the “expert’s training and experience; the facts the expert relied on; and the reasons for the expert’s opinion.” Id. The jury can reject expert testimony as long as the jury does not act arbitrarily when doing so. Conservatorship of McKeown, 30 Cal. Rpt. 2d 542 (Cal. Ct. App. 1994). In the same vein, a jury can reject an expert’s testimony even if the opposing party did not offer another expert for the jury to rely on to reject the testimony. Howard v. Owens Corning, 85 Cal. Rptr. 2d 386 (Cal. Ct. App. 1999).

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