Your words have power – Expert evidence and witness statements

Civil proceedings in Victoria are conducted in accordance with the Civil Procedure Act 2010 (Vic), the Evidence Act 2008 (Vic) and the applicable Court Rules to facilitate the just, efficient, timely and cost-effective resolution of the real issues in dispute. Expert evidence and witness statements are often used by civil litigants to advance their respective positions in legal proceedings. In light of the recent decisions handed down in Victoria and other jurisdictions, it is opportune to revisit the principles and procedures that apply to expert evidence and witness statements.

What is expert evidence?

Expert evidence is evidence of an opinion made by a person who has specialised knowledge based on their training, study or experience. Although opinion evidence is generally not admissible in courts, expert evidence is admissible in Victorian courts if the expert’s opinion is wholly or substantially based on that specialised knowledge.

Procedural and substantive requirements in relation to expert evidence

The procedural requirements in relation to expert evidence include:

  • providing the expert with a copy of the Expert Witness Code of Conduct (Code of Conduct) as soon as practicable after the expert is engaged;
  • serving the expert’s report on the other parties not later than 30 days before the day fixed for trial and delivering a copy for the use of the Court;
  • serving the supplementary report (if any) without delay; and
  • including in the report clear copies of the extrinsic material that the report refers to and ensuring that the report is signed by the expert.

A failure to satisfy the procedural and substantive requirements in the Court Rules or the Code of Conduct can cause expert evidence to become inadmissible. For example:

  • In Makita (Australia) Pty Limited v Sprowles (2001) 52 NSWLR 705, the New South Wales Court of Appeal held that if an expert’s report does not explicitly satisfy all the applicable procedural and substantive requirements, and if it is not possible to be sure whether the opinion is based wholly or substantially on the expert’s specialised knowledge, then that evidence is ‘strictly speaking not admissible and, so far as it is admissible, of diminished weight’.
  • InDasreef Pty Limited v Hawchar [2011] HCA 21, the High Court found that there was no evidence that the expert’s opinion regarding the extent of Mr Hawchar’s exposure to dust containing silica was based on the expert’s training, study or experience, despite the expert’s extensive professional credentials as a chartered chemist, chartered professional engineer and retired senior lecturer. This was because the expert had only seen the use of an angle grinder in a specific way ‘only once before’ and ‘gave no evidence that he had then, or on any other occasion, measured directly, or sought to calculate inferentially, the amount of respirable dust to which such an operator was or would be exposed’. For these reasons, the High Court concluded that the expert’s evidence was inadmissible and that the New South Wales Court of Appeal ‘was wrong to conclude that the evidence of the expert was admissible for the purposes for which that Court and the primary judge used it’.

Witness statements of lay witnesses

A witness statement is, in written form, the evidence that a witness would otherwise give orally at trial and, subject to any contrary order, will stand as the evidence in chief of the witness. It serves the purpose of supporting a plaintiff’s claim or a defendant’s defence and providing the appropriate evidence in support of such claim or defence.

In order for a witness statement to be effective and wholly admissible in court, various precautions can be taken by litigants and lawyers alike:

  • If you are a witness, tell the lawyers what evidence you intend to give without other persons in the room. If you need help with interpretation, the lawyers can engage an independent professional interpreter to help you.
  • You may be asked to provide a witness statement before proceedings are issued, not just before the final hearing of the dispute.
  • Your witness statement should be in your own ‘voice’ so that you are familiar with what is in the witness statement, and so you can confidently say that the words and language used in the witness statement are similar to what you would say in court.

What to be wary of

  • The Supreme Court of Victoria confirmed in Cargill Australia Ltd v Viterra Malt Pty Ltd (No 11) [2018] VSC 418 that legal professional privilege may be lost if a witness reviews privileged documents to refresh their memory for the purpose of giving evidence. However, privilege is maintained if the witness is simply provided with a privileged document about which he had no previous knowledge, and if its contents were unconnected to any fact or opinion about which he might be able to try to revive his memory.
  • In Fonterra Brands (Australia) Pty Ltd & Anor v Bega Cheese Ltd (No 6) [2020] VSC 96, it was held that, if a party acts in a manner inconsistent with maintaining a claim for legal professional privilege (eg by providing privileged documents to a witness to refresh their memory for the purpose of giving evidence), that privilege will be waived by such conduct.
  • The High Court’s reasons for decision in State of Queensland v The Estate of Jennifer Masson [2020] HCA 28 illustrated the importance of avoiding ‘professional drafting’ and the preference for language that accurately reflected a witness’s actual recollection and/or understanding of the relevant events (as opposed to hindsight assumptions).


Many risks are inherent in litigation, but in respect of matters that are within the control of civil litigants and their lawyers – such as the preparation of expert reports and witness statements – every measure of caution should be taken so that they can be properly prepared in satisfaction of the applicable rules of evidence. This will give your case the best chance of a successful outcome in litigation, whether at mediation or at trial.


If you have any questions about this article, please get in touch with an author or any member of our Litigation & Dispute Resolution team.


This information and the contents of this publication, current as at the date of publication, is general in nature to offer assistance to Cornwalls’ clients, prospective clients and stakeholders, and is for reference purposes only. It does not constitute legal or financial advice. If you are concerned about any topic covered, we recommend that you seek your own specific legal and financial advice before taking any action.