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  • Writer's pictureSami Abbas

Challenging the Evidence of a Single Expert

Single Expert Witness investigating Evidence

Family law proceedings often involve expert witnesses who provide specialised knowledge and opinions crucial to the case. These experts can include psychologists, social workers, child and family psychiatrists, medical specialists, property valuers, and financial consultants. Typically, these experts are appointed by one or both parties, either pursuant to a court order or through mutual agreement. The parties may commission reports from these experts to address various issues in the case, with the cost usually borne by one or both parties.

In disputes over asset valuation, such as real estate, personal property, or company interests, parties often rely on an independent expert, referred to as a single expert, to conduct a formal valuation. This process entails both parties selecting a valuer, typically from a panel of options proposed by one party, and issuing a joint letter of instruction to the chosen valuer. The letter outlines the scope of the valuation and provides necessary instructions, often including arrangements for property inspections in the case of real estate or chattels. 

In instances of disagreement with a single expert's valuation, you may seek to challenge their evidence. If a single expert report has been issued and you disagree with the valuation presented, there are steps you can take.


Clarifying the Single Expert Report

Rule 7.26 of the Federal Circuit and Family Court (Family Law) Rules 2021 (‘Family Law Rules’) allows a party to write to the expert with questions aimed at clarifying the single expert's report. These questions must be submitted within strict timelines:

  • Within 7 days of a conference with the single expert, or

  • If no conference is held, within 21 days after receiving the single expert's report.

The questions must be in writing, submitted only once, and should aim to clarify the report without being vexatious or requiring unreasonable effort from the expert. Copies of the questions must be provided to the other party.


Obtaining a ‘Shadow Report’

Before seeking court permission to present another expert's report (known as a shadow report), parties should utilise the processes of questioning and conferencing with the single expert, as emphasised in the case of Salmon and Ors & Salmon [2020] FamCAFC 134.


Federal Circuit and Family Court (Family Law) Rules 2021

Rule 7.08 of the Family Law Rules stipulates that a party cannot present a report or evidence from another expert on the same issue without the court's permission. The court may grant permission if:

  1. There is a substantial body of opinion contrary to the single expert's opinion that is necessary for determining the issue.

  2. Another expert has knowledge of matters unknown to the single expert that are necessary for determining the issue.

  3. There is another special reason for adducing evidence from another expert.


Case Study: Simonsen & Simonsen [2009] FamCA 698

The court in Simonsen & Simonsen observed that the rules do not prevent a party from obtaining their own expert evidence, which can be used to assist in cross-examining the single expert witness. However, the restrictions on communication with a single expert and the potential imbalance if one party appoints an adversarial expert while the other relies on the single expert were noted.


Case Study: Salmon and Ors & Salmon [2019] FamCA 910

In this case, Ms. Salmon commenced property settlement proceedings against Mr. Salmon after their separation. Following Ms. Salmon's death, her parents, as her legal representatives, continued the proceedings. Mr. F, a chartered accountant, was appointed as the single expert to value interests in various entities, producing three reports over several years.

Mr. W, another chartered accountant, prepared a critique of the single expert's report at Mr. Salmon's request. Mr. Salmon sought court permission to tender Mr. W's report, arguing it contained a substantial body of opinion contrary to the single expert’s findings.

When Salmon was decided the relevant legislation was the Family Law Rules 2004 (Cth). This legislation has since been replaced by the Federal Circuit and Family Court (Family Law) Rules 2021. 

In this case it was found that Part 15.5 of the Family Law Rules 2004 (Cth) aims to streamline and regulate expert evidence in family law proceedings under the Family Law Act 1975 (Cth). Rule 15.42 outlines the objectives, emphasising the restriction of expert evidence to significant disputes, the use of a single expert witness if feasible, and the avoidance of unnecessary costs.

Rule 15.49 stipulates that once a single expert is appointed, additional expert evidence can only be introduced with the court's permission under specific conditions, such as a substantial contrary opinion or unknown matters significant to the case. Rules 15.64B and 15.65 facilitate conferences and clarifications with the single expert.

The rules reflect broader judicial principles of expeditious case resolution, as seen in other jurisdictions like New South Wales and the UK. Courts generally discourage appointing multiple experts unless necessary for justice, recognising that differences in expert opinions, particularly in valuations, are common but not always sufficient to warrant additional experts. Ultimately, the court retains discretion in permitting additional expert evidence, weighing the specific circumstances of each case to ensure just, timely, and cost-effective outcomes.


In essence, the Family Law Rules provide specific guidance on handling expert evidence:

  • Rule 15.49: Allows the court to grant permission to tender another expert's report if certain conditions are met.

  • Rule 15.64B: Provides for a conference with the single expert to clarify the report.

  • Rule 15.65: Allows for questions to be posed to the single expert to seek clarification.

The purpose of these rules, as outlined in Rule 15.42, includes ensuring expert evidence is obtained only for significant issues, restricting expert evidence to what is necessary, encouraging the use of a single expert where practicable, avoiding unnecessary costs, and allowing for additional experts if necessary in the interests of justice.


The court, however, found that Mr. W's critique did not constitute a substantial body of opinion within the meaning of the rules. Furthermore, the court noted that Mr. Salmon had not utilised the available mechanisms to clarify the single expert’s report through questioning or conferencing as per the rules. The court summarises this by stating:

nothing raised by the husband or other parties have persuaded me that there is a special reason for the appointment of another expert witness, and I propose to dismiss the application.[1]



The court in Salmon and Ors & Salmon emphasised the importance of following procedural rules before seeking to introduce evidence from additional experts. The decision underlined that only in limited and justified circumstances would the court permit a party to adduce evidence from additional experts when a single expert has already been appointed. This ensures that expert evidence remains focused on significant issues in dispute and avoids unnecessary costs, maintaining the integrity and efficiency of the judicial process.


Disclaimer: The information provided here is for educational purposes only and should not be considered legal advice. If you need legal assistance, we recommend contacting Carter Dickens Lawyers or consulting a qualified attorney. Legal matters can vary based on laws and regulations, and it is important to seek professional advice for your specific

[1] Salmon and Ors & Salmon [2019] FamCA 910, [35].

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