California Civil Jury Instructions (CACI)

221. Conflicting Expert Testimony

If the expert witnesses disagreed with one another, you should weigh each opinion against the others. You should examine the reasons given for each opinion and the facts or other matters that each witness relied on. You may also compare the experts’ qualifications.

New September 2003

Directions for Use

Unless the issue is one that can be resolved only with expert testimony, the jury should not be instructed that they must accept the entire testimony of the expert whose testimony appears to be entitled to greater weight. (Santa Clara County Flood Control and Water Conservation Dist. v. Freitas (1960) 177 Cal.App.2d 264, 268–269 [2 Cal.Rptr. 129].)

For an instruction on expert witnesses generally, see CACI No. 219, Expert Witness Testimony. For an instruction on hypothetical questions, see CACI No. 220, Experts—Questions Containing Assumed Facts.

Sources and Authority

  • Santa Clara County Flood Control and Water Conservation Dist., supra, 177 Cal.App.2d at p. 268.
  • 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].)

Secondary Sources

7 Witkin, California Procedure (4th ed. 1997) Trial, § 303

48 California Forms of Pleading and Practice, Ch. 551, Trial, § 551.70 (Matthew Bender)