Expert reports often contain hearsay evidence. This is especially true in personal injury cases where expert witnesses review pages upon pages of clinical notes of other physicians in arriving at their opinions. Today the BC Court of Appeal released useful reasons for judgement confirming that hearsay evidence does not render an expert report inadmissible. The Court further noted that some types of hearsay evidence in expert reports, even if not independently proven at trial, does not necessarily nullify the experts opinion.
In today’s case (Mazur v. Lucas) the Plaintiff was injured in a 2006 BC motor vehicle collision. At trial the Plaintiff tendered the report of a psychiatrist. The trial judge ordered that hearsay portions of the report be redacted and did not permit opposing counsel to cross examine the expert with respect to the redacted portions of the report. Ultimately the Jury awarded the Plaintiff $528,400 in damages.
The Defendant appealed arguing that the trial judge incorrectly redacted hearsay from the expert reports and unreasonably restricted the cross-examination. The BC High Court agreed and ordered a new trial. In doing so the Court repeated the following very useful quote from Mr. Justice Sopinka addressing the reality of hearsay in medical diagnosis:
“A physician, for example, daily determines questions of immense importance on the basis of the observations of colleagues, often in the form of second- or third-hand hearsay. For a court to accord no weight to, or to exclude, this sort of professional judgment, arrived at in accordance with sound medical practices, would be to ignore the strong circumstantial guarantees of trustworthiness that surround it, and would be, in my view, contrary to the approach this Court has taken to the analysis of hearsay evidence in general, exemplified in Ares v. Venner,  S.C.R. 608”
The BC Court of Appeal went on to provide the following useful summary of hearsay evidence in expert reports in personal injury lawsuits:
 From these authorities, I would summarize the law on this question as to the admissibility of expert reports containing hearsay evidence as follows:
· An expert witness may rely on a variety of sources and resources in opining on the question posed to him. These may include his own intellectual resources, observations or tests, as well as his review of other experts’ observations and opinions, research and treatises, information from others – this list is not exhaustive. (See Bryant, The Law of Evidence in Canada, at 834-835)
· An expert may rely on hearsay. One common example in a personal injury context would be the observations of a radiologist contained in an x-ray report. Another physician may consider it unnecessary to view the actual x-ray himself, preferring to rely on the radiologist’s report.
· The weight the trier of fact ultimately places on the opinion of the expert may depend on the degree to which the underlying assumptions have been proven by other admissible evidence. The weight of the expert opinion may also depend on the reliability of the hearsay, where that hearsay is not proven by other admissible evidence. Where the hearsay evidence (such as the opinion of other physicians) is an accepted means of decision making within that expert’s expertise, the hearsay may have greater reliability.
· The correct judicial response to the question of the admissibility of hearsay evidence in an expert opinion is not to withdraw the evidence from the trier of fact unless, of course, there are some other factors at play such that it will be prejudicial to one party, but rather to address the weight of the opinion and the reliability of the hearsay in an appropriate self-instruction or instruction to a jury.
 The common law is supplemented by the Rules of Court concerning expert reports. The Rules of Court in force at the time of this trial required an expert to state “the facts and assumptions upon which the opinion is based”. (Rule 40A(5)(b)). Rule 11-6(1) which replaces Rule 40A requires the expert to state:
(f) the expert’s reasons for his or her opinion, including
(i) a description of the factual assumptions on which the opinion is based,
(ii) a description of any research conducted by the expert that led him or her to form the opinion, and
(iii) a list of every document, if any, relied on by the expert in forming the opinion.
 New Rule 11-6 expands on what an expert was required to state under old Rule 40A, but does not alter the general principle that it is essential for the trier of fact to know the basis of an expert opinion so that the opinion can be evaluated. The Rule has a dual purpose. The second purpose is to allow the opposing party to know the basis of the expert’s opinion so that they or their counsel can properly prepare for, and conduct, cross-examination of the expert, and if appropriate, secure a responsive expert opinion. Thus, the result of these reasons would be the same if this case had arisen under the new Rules. There is nothing in these Rules touching directly on the question of the admissibility of hearsay evidence in expert reports.
I have previously written (here and here) that Plaintiff’s need to be wary if relying on a radiologists findings in support of a personal injury claim at trial and ensure that the evidence is independently proven at trial. Today’s case appears to potentially soften this requirement somewhat.