Expert Witness Testimony under California’s Evidence Code

Division 7 of the California Evidence Code deals with Opinion Testimony and Scientific Evidence. Chapter 1 concerns Expert and Other Opinion Testimony. Article 1 is on expert and other opinion testimony generally. Section 800 states that, if a witness is not testifying as an expert, his testimony in the form of an opinion is limited to such an opinion as is permitted by law, including but not limited to an opinion that is rationally based on the perception of the witness and helpful to a clear understanding of his testimony.

Section 801 provides that, if a witness is testifying as an expert, his testimony in the form of an opinion is limited to such an opinion as is related to a subject that is sufficiently beyond common experience that the opinion of an expert would assist the trier of fact; and based on matter (including his special knowledge, skill, experience, training, and education) perceived by or personally known to the witness or made known to him at or before the hearing, whether or not admissible, that is of a type that reasonably may be relied upon by an expert in forming an opinion upon the subject to which his testimony relates, unless an expert is precluded by law from using such matter as a basis for his opinion.

Section 801.1 states that, in a general civil case, where the party bearing the burden of proof proffers expert testimony regarding medical causation and where that party’s expert is required as a condition of testifying to opine that causation exists to a reasonable medical probability, the party not bearing the burden of proof may offer a contrary expert only if its expert is able to opine that the proffered alternative cause or causes each exists to a reasonable medical probability.

Section 802 provides that a witness testifying in the form of an opinion may state on direct examination the reasons for his opinion and the matter (including, in the case of an expert, his special knowledge, skill, experience, training, and education) upon which it is based, unless he is precluded by law from using such reasons or matter as a basis for his opinion.

Section 803 allows a court to exclude testimony in the form of an opinion that is based in whole or in significant part on matter that is not a proper basis for such an opinion.

Section 804 specifies that, if a witness testifying as an expert testifies that his opinion is based in whole or in part upon the opinion or statement of another person, that other person may be called and examined by any adverse party as if under cross-examination concerning the opinion or statement. This section does not apply in specified instances.

Section 805 provides that testimony 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.

Article 2 concerns Evidence of Market Value of Property. Section 810 states that this article provides special rules of evidence applicable to any action in which the value of property is to be ascertained. However, this article does not govern ad valorem property tax assessment or equalization proceedings.

Section 811 defines the phrase “value of property.” Section 812 states that this article is not intended to alter or change the existing substantive law, whether statutory or decisional, interpreting the meaning of “market value,” whether denominated “fair market value” or otherwise.

Section 813 provides that the value of property may be shown only by the opinions of witnesses qualified to express such opinions; the owner or the spouse of the owner of the property or property interest being valued; or an officer, regular employee, or partner designated by a corporation, partnership, or unincorporated association that is the owner of the property or property interest being valued, if the designee is knowledgeable as to the value of the property or property interest.

Section 814 specifies that the opinion of a witness as to the value of property is limited to such an opinion as is based on matter perceived by or personally known to the witness or made known to the witness at or before the hearing, whether or not admissible, that is of a type that reasonably may be relied upon by an expert in forming an opinion as to the value of property.

Section 815 states that, when relevant to the determination of the value of property, a witness may take into account as a basis for an opinion the price and other terms and circumstances of any sale or contract to sell and purchase which included the property or property interest being valued or any part thereof if the sale or contract was freely made in good faith within a reasonable time before or after the date of valuation, with specified exceptions.

Section 816 provides that, when relevant to the determination of the value of property, a witness may take into account as a basis for his opinion the price and other terms and circumstances of any sale or contract to sell and purchase comparable property if the sale or contract was freely made in good faith within a reasonable time before or after the date of valuation. There are rules regarding what is to be considered comparable.

Section 817 states that, when relevant to the determination of the value of property, a witness may take into account as a basis for an opinion the rent reserved and other terms and circumstances of any lease which included the property or property interest being valued or any part thereof which was in effect within a reasonable time before or after the date of valuation, with specified exceptions.

Section 818 provides rules for determining the capitalized value of the reasonable net rental value attributable to the property or property interest being valued or determining the value of a leasehold interest.

Section 819 states that, when relevant to the determination of the value of property, a witness may take into account as a basis for his opinion the capitalized value of the reasonable net rental value attributable to the land and existing improvements thereon (as distinguished from the capitalized value of the income or profits attributable to the business conducted thereon).

Section 820 specifies that, when relevant to the determination of the value of property, a witness may take into account as a basis for his opinion the value of the property or property interest being valued as indicated by the value of the land together with the cost of replacing or reproducing the existing improvements thereon, if the improvements enhance the value of the property or property interest for its highest and best use, less whatever depreciation or obsolescence the improvements have suffered.

Section 821 states that, when relevant to the determination of the value of property, a witness may take into account as a basis for his opinion the nature of the improvements on properties in the general vicinity of the property or property interest being valued and the character of the existing uses being made of such properties.

Section 822 provides that, in an eminent domain or inverse condemnation proceeding, specified matters are inadmissible as evidence and cannot be taken into account as a basis for an opinion as to the value of property.

Section 823 states that the value of property for which there is no relevant, comparable market may be determined by any method of valuation that is just and equitable.

Section 824 explains that a just and equitable method of determining the value of nonprofit, special use property, for which there is no relevant, comparable market, is the cost of purchasing land and the reasonable cost of making it suitable for the conduct of the same nonprofit, special use, together with the cost of constructing similar improvements. The method for determining compensation for improvements is established in this section.

Article 3 deals with Opinion Testimony on Particular Subjects. Section 870 provides that a witness may state his opinion as to the sanity of a person in the following circumstances: the witness is an intimate acquaintance of the person whose sanity is in question; the witness was a subscribing witness to a writing, the validity of which is in dispute, signed by the person whose sanity is in question and the opinion relates to the sanity of such person at the time the writing was signed; or the witness is qualified to testify in the form of an opinion.