Express Law No. 314

28 June 2023

Guidance on briefing expert witnesses – the recent decision in New Aim v Leung

The recent decision of the Full Court of the Federal Court of Australia (the Court) in New Aim Pty Ltd v Leung [2023] FCAFC 67 (Appeal Judgment) provides some clarification of what is permissible when lawyers are preparing expert evidence, including communications with the expert. However, the Court stopped short of identifying hard and fast rules. Instead, it emphasised that whether it is appropriate or desirable to involve experts in refining the questions that they will be asked to address, or to disclose the involvement of solicitors in preparing the report and communicating with the expert, will depend on any number of circumstances peculiar to the case.

Key takeaways

  • Expert reports, and any letters of instruction annexed to the report, should be transparent about the process through which the expert report was prepared. Importantly, questions that the expert has been asked to address must be disclosed in the expert report.
  • Legal practitioners must take care to ensure they are not involved in the preparation of an expert report to the extent that they influence, or are seen to influence, the expert’s opinion. The permissible involvement of legal practitioners in preparing an expert report and the extent to which that involvement needs to be disclosed depends on the circumstances.
  • Sending a final letter of instruction shortly before an expert report is finalised is not necessarily impermissible, so long as it is clear to the Court what material has been provided to the expert and what questions the expert was asked to address.

Factual background

In New Aim, the applicant’s solicitors retained an independent expert, Ms Chen, the Managing Director of ChinaDirect Sourcing Services Pty Ltd, to give evidence about how information about the identities and details of suppliers in China is commonly used in the e-commerce industry.[1] The solicitors engaged Ms Chen in late February 2022. Shortly afterwards, Ms Chen provided her biography, a ‘script’ about ChinaDirect Sourcing and a sample product inspection report, which were used by the solicitors to assist in preparing the expert report with Ms Chen. On 7 March 2022, the solicitors sent a letter of instruction to Ms Chen and the following day, Ms Chen’s report was finalised.

The decision at first instance

At first instance, the primary judge rejected Ms Chen’s written and oral evidence in its entirety for 3 reasons.[2]

  1. First, the primary judge found that Ms Chen’s evidence was not independent, as it was not clear whether the majority of the report had been drafted by Ms Chen or the solicitors who engaged her. As a result, the process of preparing the report, according to the primary judge, went ‘well beyond permissible guidance [as to form and evidentiary requirements]’ to the extent that it was unclear which parts of the report Ms Chen had drafted herself.[3]
  2. Secondly, the primary judge found that because of the solicitors’ involvement in the preparation of the report, clause 3.2 of the Federal Court Expert Evidence Practice Note – which advises parties and legal representatives to be cautious not to have inappropriate communications with an expert or assist them in preparing their evidence – was not complied with.[4] Further, the expert’s paramount duty to assist the court impartially was ‘substantially undermined’ by the failure to disclose the process for preparing the expert report.[5]
  3. Thirdly, the primary judge found that the letter of instruction, which was dated one day before the report was finalised, contained misleading representations in relation to the timing and process for preparing the report.[6] As a draft report had been prepared by Corrs no later than 25 February 2022, the primary judge found it was wrong to state in the 7 March 2022 letter that Ms Chen was instructed to prepare a report. This was because the date on the letter of instruction suggested that Ms Chen ‘would upon receipt of the instruction set about the task of preparing her report’, when – at the time of sending the letter – the solicitors were already aware of what the answers would be and the form of the opinion. The primary judge observed that this practice of sending letters of instructions to experts late in the process ‘strikes at the very heart of the paramount and overriding duty that an independent expert has to assist the court impartially on matters relevant to the area of expertise of the witness’.[7]

The decision on appeal

On appeal, the Full Court found that the primary judge erred in rejecting the entirety of Ms Chen’s expert report. In doing so, the Full Court commented on the obligations of solicitors when instructing and otherwise communicating with expert witnesses.

First, in some circumstances, it is permissible for solicitors to be involved in drafting parts of an expert report. For example, the Full Court noted that ‘the drafting of written evidence of a factual nature from a statement or other material provided by a witness is far from unusual’.[8] However, if legal practitioners are to be involved in drafting an expert report, the Full Court cautioned that the legal practitioner should take care not to influence the expert’s evidence and should draft the report based on what the expert has communicated.[9] Importantly, Ms Chen’s report contained both factual and opinion evidence and the Full Court made clear that the duty not to influence a witness’s evidence applies to witnesses of fact as well as experts.[10]

While the primary judge considered that the involvement of legal practitioners in drafting an expert report must be disclosed in the report, the Full Court on appeal found that this ‘may well be desirable, forensically or otherwise, but there is no legal obligation as such to do so’. They went on to say that the existence of an ethical obligation to disclose the involvement of lawyers depends on the particular circumstances of the case.[11] The Full Court did not describe when this obligation would arise. But it perhaps follows from the general discussion that there will be an ethical obligation to disclose a solicitor’s involvement in drafting the expert report if the solicitor has influenced the expert’s opinion, for example, because the drafting of the report is not based on what the expert communicated to the solicitor.

The 24-hour timeframe between the letter of instructions and the expert report being finalised did not raise particular concerns for the Full Court, which noted that ‘it is not unusual for a final letter of instructions, containing the final form of the questions to be answered by an expert, to be prepared shortly before an expert report is finalised’.[12]

Ultimately, the Full Court emphasised that the process of instructing the expert should be transparent so the questions the expert has been asked to address are clear. But it acknowledged that what is ‘appropriate or desirable’ when seeking an expert’s input on the questions they are being asked to address and disclosing that input ‘depends on any number of circumstances peculiar to the particular case and different, equally proper, approaches can be expected from different legal practitioners’.[13]

The Full Court ultimately ordered a retrial before another single judge of the Federal Court. The retrial may provide further useful commentary on Ms Chen’s expert report and the process by which it was prepared.

Practical implications

While the Full Court refrained from setting down any ‘hard and fast’ rules for briefing and instructing expert witnesses, agencies should bear in mind that the process of engaging with the expert should be transparently set out in the expert report. While the Full Court left it open to solicitors to determine the appropriate process for instructing experts and preparing expert reports, it provided some examples of solicitor involvement in preparing expert reports that may be permissible, such as:

  • solicitors engaging with experts about framing questions to be addressed in an expert report in a logical way that identifies the real issues, where the subject matter involves a specialised field of scientific knowledge[14]
  • solicitors drafting written evidence of a factual nature based on material provided by a witness[15]
  • solicitors assisting with drafting where there are physical, language or resource difficulties (although where this occurs, legal practitioners should draft the report from what the expert has communicated to them and should take care to ensure they do not suggest what the expert’s evidence should be).[16]

As Courts have emphasised on several occasions, the extent to which involvement in the preparation of an expert report is permissible will depend on the circumstances of the case. If there is any doubt about whether certain communications with an expert witness are permissible, agencies should seek legal advice.

[1] New Aim v Leung [2022] FCA 722 (Primary Judgment) at [45], [47].

[2] Ibid, [70]-[74].

[3] Ibid, [63], [70].

[4] Ibid, [70]-[71].

[5] Ibid, [2].

[6] Ibid, [74].

[7] Ibid, [75].

[8] Appeal Judgment, [112].

[9] Appeal Judgment, [120].

[10] Appeal Judgment, [119].

[11] Appeal Judgment at [121]-[123].

[12] Appeal Judgment, [87].

[13] Appeal Judgment at [89].

[14] Appeal Judgment at [89].

[15] Appeal Judgment at [112].

[16] Appeal Judgment at [120].


Daley PSM, Simon

Chief Solicitor Dispute Resolution

Tate, Alexander

A/g Senior Executive Lawyer and Director Brisbane office

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