Assumptions made by experts – proof of the truth of statements made and objections October 26, 2017
 McMeekin J has mentioned, in Robert Bax & Associates v Cavenham Pty Ltd Muir JA articulated the principle that, “generally speaking at least, a party who fails to object to inadmissible hearsay evidence contained in a document which is admissible as original evidence will have waived its right to limit the use to which the evidence may be put”. Whilst I respectfully agree with the decision in that case, I share McMeekin J’s doubt whether such a principle generally applies in relation to statements in expert reports of asserted facts upon which the expert’s opinion is based.
 There may be cases in which an expert’s statement of another person’s assertion of a fact is admissible as original evidence of that fact (see, for example, Gordon v R, concerning some statements made to a psychiatrist), but such cases are exceptional. In most cases, an expert’s statement of a fact asserted by another person is not admissible evidence of the truth of that fact. The common law position in this respect is succinctly summarised in the High Court’s restatement in Gordon v R of the principle expressed in Ramsay v Watson: “… statements made to an expert witness are admissible if they are the foundation, or part of the foundation, of the expert opinion to which he testifies but that if such statements, being hearsay, are not confirmed in evidence, the expert testimony based on them is of little or no value.” Other than in exceptional cases, that authoritative statement seems to require the conclusion that whilst an expert’s statement of a fact forming a basis of the expert’s opinion is admissible, it is not to be treated as evidence of the truth of that fact. Consistently with that view, and as McMeekin J has noted, the Uniform Civil Procedure Rules1999 (Qld) requires an expert to identify the factual bases of the expert’s opinion. Rule 428(2) provides that an expert report “must include the following information – (b) all material facts, whether written or oral, on which the report is based”. It is not to be supposed that the purpose of this rule was to provide a shortcut to the proof of a fact upon which an expert’s opinion is based.
 With that background in mind, a record in an expert report of a fact asserted by another person upon which the expert’s opinion is based ordinarily would not be construed as involving any statement about the truth of the fact. Instead, it would be understood as the expert’s identification of a fact assumed to be true only for the purpose of the expert formulating his or her opinion. Upon that basis, it is difficult to see the need for an opposing party to make any statement to that effect, or to object to the admission in evidence of the recorded fact, in order to avoid the admission of the report being treated as evidence of the truth of that fact. There may be particular cases in which the circumstances make it prudent for a party to clarify the position, or even to take an objection, but ordinarily the mere absence of an objection should not transform an expert’s statement of a fact upon which the expert’s opinion is based into evidence of the truth of that fact.