If you are involved in a planning dispute, whether as a developer or objector, it may be necessary or beneficial to retain an expert witness.

The role of an expert witness in a dispute is to provide objective, qualified, documented evidence of the facts in dispute.

Engaging an expert witness can be a complex and expensive exercise and the expert’s role as an impartial observer, and not an advocate for the instructing party, is often misunderstood.

Parties to a dispute can become anxious when it appears that the expert they have retained is not ‘on their side’ or that the other party’s expert is an ‘opponent’ in disputed proceedings. It is therefore helpful to understand the role of expert witnesses, their obligations to a tribunal or court and how they can assist in determining a dispute.

What is an expert witness?

An expert witness is a qualified professional with specialised technical knowledge in a particular area or industry and the necessary skills to provide an opinion, in writing and verbally. This opinion may be used as evidence in negotiations, dispute resolution processes or during tribunal or court proceedings.

When and why is an expert used?

The role of the expert is to assist the parties in negotiating a settlement, or if the matter proceeds to a tribunal or court, guide it towards a reasonable determination.

A planning dispute does not typically concern the interpretation of a contractual term, which, in a court or tribunal, would be a matter for lawyers to prepare submissions and advocate on behalf of their respective clients.

A layperson is not qualified to provide evidence of a technical nature which, in court or tribunal proceedings, could be considered an opinion or hearsay. In such matters evidence should be given by a person with specialised knowledge in the subject matter based on his or her training, study or experience. An expert witness provides evidence based on his or her area of expertise and may be cross examined in respect of that evidence. The testing of this evidence can provide more weight in a dispute than submissions made by lawyers.

Retaining an expert witness

The selection of an appropriate expert witness is typically suggested by the lawyer representing a party to the dispute, who will identify a professional with the necessary expertise required for the particular case and the ability to provide written, and oral evidence, if required.

Written instructions should be provided to the expert which will include an overview of the matter, the issues in dispute, the matters to be addressed, and additional information that will assist in compiling the report, such as the development application, plans, and the consent authority’s report regarding the decision in dispute.

Tribunals and courts have specific rules and codes of conduct regarding the use of an expert witness and the required format for expert reports to ensure consistency and uniformity. A copy of the relevant expert evidence guidelines and reporting requirements from the tribunal should always accompany the instructions.

The expert report

An expert will draw upon his or her expert knowledge to provide a qualified opinion in response to the issues raised in the instructions. A report will typically include:

  • the expert’s formal qualifications, experience and field of expertise in which the evidence is being provided;
  • a summary of the issues upon which the expert is required to report;
  • any facts or assumptions upon which the expert has relied (i.e. the letter of instruction);
  • identification of the points of contention;
  • an opinion regarding the development’s compliance with State Environmental Planning Policies, Local Environmental Planning Policies, and Development Control Plans;
  • any inspections, investigations or tests used to form the opinion.

The duty of impartiality

Tribunal and court rules, practice notes and directions require that an expert witness is impartial and not an advocate for a party to a proceeding. He or she has an overriding duty to assist a tribunal or court on the matter relevant to the expert’s expertise.

Independence is paramount and any hint of bias towards the instructing party by the expert can be detrimental to that party’s case and may initiate a request by the opposing side for the tribunal to disregard that expert’s evidence.

The expert’s reputation and credibility in such circumstances will also be at stake.


An expert witness may be retained to provide an impartial qualified opinion to assist in determining a matter in dispute.

Choosing an expert with the requisite qualifications, knowledge and experience to provide an objective opinion (and understanding that an expert is not an advocate for the instructing party) is essential for all disputes.

If you or someone you know wants more information or needs help or advice, please contact us on 0409 007 794 or email [email protected].