Management of Expert Witnesses

Commercial Law
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An expert is a person who has experience or expertise in a subject calling for special skill or knowledge. There must be a field of specialised knowledge identified. Such a witness can give opinions within his area of expertise, and is not limited to giving evidence of facts as are other witnesses.

What is an expert witness?

An expert is a person who has experience or expertise in a subject calling for special skill or knowledge. There must be a field of specialised knowledge identified. Such a witness can give opinions within his area of expertise, and is not limited to giving evidence of facts as are other witnesses: Evidence Act 1995 (Cth) section 76 (rule against admissibility of opinion evidence) and section 79 (exception for opinion evidence based on specialised knowledge); see also the equivalent provisions in the Evidence Act 2008 (Vic). The Trial Judge must (first) decide whether the field of knowledge in which the witness professes expertise is a recognised and organised body of knowledge, outside the ordinary experience of men. The Trial Judge must (second) decide whether the opinion expressed in evidence by the expert witness is wholly or substantially based on that knowledge. Unless at least each of these elements is satisfied, the evidence of the witness concerned is inadmissible.

What are experts used for?

Primarily, expert witnesses are used in civil proceedings to give evidence on technical matters requiring opinion evidence which non-expert witnesses are unable (and not allowed) to give. Examples include medical opinions as to whether the Plaintiff worker is suffering from a claimed injury; evidence as to whether an engineering structure was designed and/or constructed satisfactorily or whether the structure’s failure was due to factors for which the architect and/or builder was not responsible; valuation evidence of a business, shares in a company or other assets such as options (call or put) concerning shares in a company or other securities; whether the actions taken by a mortgagee to sell real property were reasonable having regard to the mortgagee’s duty under section 77 of the Transfer of Land Act 1958 (Vic); pharmaceutical or medical evidence about the efficacy of a drug; evidence as to the state of the prior art before the priority date of a challenged patent, the meaning of terms of art used in a patent specification, what was obvious to a person skilled in the art at the priority date, the status of reputation, and so forth.

Section 76(1) of the Evidence Act expresses the opinion rule in a way which assumes that evidence of an opinion is tendered "to prove the existence of a fact". The opinion rule is expressed in this way in order to direct attention to why the party tendering the evidence says it is relevant. More particularly, it directs attention to the finding which the tendering party will ask the tribunal of fact to make. In considering the operation of section 79(1), it is thus necessary to identify why the evidence is relevant: why it is "evidence that, if it were accepted, could rationally affect (directly or indirectly) the assessment of the probability of the existence of a fact in issue in the proceeding". Evidence may also be taken from expert witnesses in Court by using the concurrent evidence or “hot tub” technique. In fact, Hot Tubs are the preferred form of delivery of expert evidence favoured by many judges. The court may also direct expert witnesses to confer outside Court and to provide the Court with a joint report specifying matters agreed and matters not agreed and the reasons for their not agreeing.

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Tomaso Di Lallo has an extensive commercial law practice in the Supreme and Federal Courts

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