CACI 219 Expert Witness Testimony
California Civil Jury Instructions CACI
219 Expert Witness Testimony
During the trial you heard testimony from expert witnesses. The law allows an expert to state opinions about matters in the expert’s field of expertise even if the expert has not witnessed any of the events involved in the trial.
You do not have to accept an expert’s opinion. As with any other witness, it is up to you to decide whether you believe the expert’s testimony and choose to use it as a basis for your decision. You may believe all, part, or none of an expert’s testimony. In deciding whether to believe an expert’s testimony, you should consider:
a. The expert’s training and experience;
b. The facts the expert relied on; and
c. The reasons for the expert’s opinion.
New September 2003; Revised May 2020
This instruction should not be given for expert witness testimony on the standard of care in professional malpractice cases if the testimony is uncontradicted. Uncontradicted testimony of an expert witness on the standard of care in a professional malpractice case is conclusive. (Howard v. Owens Corning (1999) 72 Cal.App.4th 621, 632–633 [85 Cal.Rptr.2d 386]; Conservatorship of McKeown (1994) 25 Cal.App.4th 502, 509 [30 Cal.Rptr.2d 542]; Lysick v. Walcom (1968) 258 Cal.App.2d 136, 156 [65 Cal.Rptr. 406].) In all other cases, the jury may reject expert testimony, provided that the jury does not act arbitrarily. (McKeown, supra, 25 Cal.App.4th at p. 509.)
Do not use this instruction in eminent domain and inverse condemnation cases. (See Aetna Life and Casualty Co. v. City of Los Angeles (1985) 170 Cal.App.3d 865, 877 [216 Cal.Rptr. 831]; CACI No. 3515, Valuation Testimony.)
For an instruction on hypothetical questions, see CACI No. 220, Experts—Questions Containing Assumed Facts. For an instruction on conflicting expert testimony, see CACI No. 221, Conflicting Expert Testimony.
• Qualification as Expert. Evidence Code section 720(a).
• “ ‘A properly qualified expert may offer an opinion relating to a subject that is beyond common experience, if that expert’s opinion will assist the trier of fact.’ ‘However, even when the witness qualifies as an expert, he or she does not possess a carte blanche to express any opinion within the area of expertise. [Citation.] For example, an expert’s opinion based on assumptions of fact without evidentiary support [citation], or on speculative or conjectural factors [citation], has no evidentiary value [citation] and may be excluded from evidence. [Citations.] Similarly, when an expert’s opinion is purely conclusory because unaccompanied by a reasoned explanation connecting the factual predicates to the ultimate conclusion, that opinion has no evidentiary value because an “expert opinion is worth no more than the reasons upon which it rests.” ’ ‘An expert who gives only a conclusory opinion does not assist the jury to determine what occurred, but instead supplants the jury by declaring what occurred.’ ” (Property California SCJLW One Corp. v. Leamy (2018) 25 Cal.App.5th 1155, 1163 [236 Cal.Rptr.3d 500], internal citation omitted.)
• “Under Evidence Code section 720, subdivision (a), a person is qualified to testify as an expert if he or she ‘has special knowledge, skill, experience, training, or education sufficient to qualify him as an expert on the subject to which his testimony relates.’ ‘[T]he determinative issue in each case must be whether the witness has sufficient skill or experience in the field so that his testimony would be likely to assist the jury in the search for the truth … . [Citation.] Where a witness has disclosed sufficient knowledge, the question of the degree of knowledge goes more to the weight of the evidence than its admissibility. [Citation.]’ ” (Lattimore v. Dickey (2015) 239 Cal.App.4th 959, 969 [191 Cal.Rptr.3d 766].)
• The “credibility of expert witnesses is a matter for the jury after proper instructions from the court.” (Williams v. Volkswagenwerk Aktiengesellschaft (1986) 180 Cal.App.3d 1244, 1265 [226 Cal.Rptr. 306].)
• “[U]nder Evidence Code sections 801, subdivision (b), and 802, the trial court acts as a gatekeeper to exclude expert opinion testimony that is (1) based on matter of a type on which an expert may not reasonably rely, (2) based on reasons unsupported by the material on which the expert relies, or (3) speculative. Other provisions of law, including decisional law, may also provide reasons for excluding expert opinion testimony. [¶] But courts must also be cautious in excluding expert testimony. The trial court’s gatekeeping role does not involve choosing between competing expert opinions.” (Sargon Enterprises, Inc. v. University of Southern California (2012) 55 Cal.4th 747, 771−772 [149 Cal.Rptr.3d 614, 288 P.3d 1237], footnote omitted.)
• “ ‘Generally, the opinion of an expert is admissible when it is “[r]elated to a subject that is sufficiently beyond common experience that the opinion of an expert would assist the trier of fact … .” [Citations.] Also, “[t]estimony in the form of an opinion that is otherwise admissible is not objectionable because it embraces the ultimate issue to be decided by the trier of fact.” [Citation.] However, “ ‘Where the jury is just as competent as the expert to consider and weigh the evidence and draw the necessary conclusions, then the need for expert testimony evaporates.’ ” ’ Expert testimony will be excluded ‘ “ ‘when it would add nothing at all to the jury’s common fund of information, i.e., when ‘the subject of inquiry is one of such common knowledge that men of ordinary education could reach a conclusion as intelligently as the witness.” ’ ” ’ ” (Burton v. Sanner (2012) 207 Cal.App.4th 12, 19 [142 Cal.Rptr.3d 782], internal citations omitted.)
• Under Evidence Code section 801(a), expert witness testimony “must relate to a subject that is sufficiently beyond common experience that the opinion of an expert would assist the trier of fact.” (New v. Consolidated Rock Products Co. (1985) 171 Cal.App.3d 681, 692 [217 Cal.Rptr. 522].)
• Expert witnesses are qualified by special knowledge to form opinions on facts that they have not personally witnessed. (Manney v. Housing Authority of The City of Richmond (1947) 79 Cal.App.2d 453, 460 [180 P.2d 69].)
• “Although a jury may not arbitrarily or unreasonably disregard the testimony of an expert, it is not bound by the expert’s opinion. Instead, it must give to each opinion the weight which it finds the opinion deserves. So long as it does not do so arbitrarily, a jury may entirely reject the testimony of a plaintiff’s expert, even where the defendant does not call any opposing expert and the expert testimony is not contradicted.” (Howard, supra, 72 Cal.App.4th at p. 633, citations omitted.)
• “When any expert relates to the jury case-specific out-of-court statements, and treats the content of those statements as true and accurate to support the expert’s opinion, the statements are hearsay. It cannot logically be maintained that the statements are not being admitted for their truth.” (People v. Sanchez (2016) 63 Cal.4th 665, 686 [204 Cal.Rptr.3d 102, 374 P.3d 320].)
• “Any expert may still rely on hearsay in forming an opinion, and may tell the jury in general terms that he did so. Because the jury must independently evaluate the probative value of an expert’s testimony, Evidence Code section 802 properly allows an expert to relate generally the kind and source of the ‘matter’ upon which his opinion rests. A jury may repose greater confidence in an expert who relies upon well-established scientific principles. It may accord less weight to the views of an expert who relies on a single article from an obscure journal or on a lone experiment whose results cannot be replicated. There is a distinction to be made between allowing an expert to describe the type or source of the matter relied upon as opposed to presenting, as fact, case-specific hearsay that does not otherwise fall under a statutory exception.” (People v. Sanchez, supra, 63 Cal.4th at pp. 685–686, original italics.)