Extensive communications between lawyers and independent experts are not unusual in complex legal disputes, such as delay and disruption claims in construction and infrastructure disputes. Those communications will usually be privileged if the dominant purpose of the communication was to provide legal services in relation to a legal proceeding. However, it is widely recognised that when a final expert report is tendered or served on another party this may result in waiver of privilege in relation to communications between lawyers and experts that influenced the substance of the report. Justice Riordan's judgment in Finance Guarantee Company Pty Ltd v Auswild (Expert Evidence Ruling)  VSC 665 (Expert Evidence Ruling) provides guidance on this test.
Finance Guarantee Company Pty Ltd v Auswild (Expert Evidence Ruling)
Justice Riordan of the Supreme Court in his recent Expert Evidence Ruling confirmed that communications between lawyers and experts are permissible and will not impede the expert's impartiality as long as there is no attempt to influence the expert's opinion. He confirmed that there is nothing unusual or wrong with the lawyers briefing the expert prior to issuing a letter of instruction for a complicated matter, and it would be unusual if this did not occur. It is to be expected that there will be communications for the purpose of identifying the pertinent questions and relevant material. His Honour also observed that there is nothing improper in a lawyer putting a proposition or "thesis" to an expert and asking whether the relevant facts support this thesis or proposition; as long as this is not influencing the expert's opinion.
His Honour explained that what will be appropriate will depend on the circumstances. For a less experienced expert a greater level of communication will likely be required to assist the expert to prepare their report in an admissible form. While the context is relevant the ultimate question is whether the communications disclose an attempt to influence the expert or undermine the expert's independence.
Justice Riordan also ruled that communications which the expert considered but which did not form the basis of the expert's opinion do not need to be disclosed and privilege will not necessarily be waived in relation to these communications.
Principles relating to expert reports and waiver of privilege
This is consistent with established law in relation to waiver of privilege. The High Court in Mann v Carnell (1999) 201 CLR 1 determined that whether privilege will be waived in an associated communication or draft report by an action such as serving the expert report on the other side will depend on whether it will be inconsistent to maintain confidentiality in the communication or draft report following this action being taken. A second basis is whether the disclosure of the communication or draft report is necessary to thoroughly understand the report.
The courts have interpreted the relevant test for inconsistency as not relating to some general notion of unfairness, but as depending on whether the communication or draft report influenced the substantive content of the final report. This means that there will be no waiver in relation to communications that have not improperly influenced the substantive content of the report and are limited to ensuring it is in admissible form. Such communication is proper, and is in fact required in the case of inexperienced experts who may not otherwise be familiar with admissibility requirements. In New Cap Reinsurance Corporation (In Liq) v Renaissance Reinsurance Ltd  NSWSC 258 and subsequent cases, it was determined that disclosure of communications is not necessary in relation to communications that influenced the substantive content but were properly referred to in the report, as required by the Expert Code. This would extend to communications that provided assumptions or material relied on in the report, which were properly explained and referred to in the final report.
- Some communication will be necessary for the lawyers to fulfil their obligations to test the expert witness's evidence and to ensure that the expert report is in admissible form.
- As long as there are no attempts made to interfere with the expert's independence, communicating with the expert will generally not be considered improper.
- Finally, as long as the entire bases for all opinions in the report are adequately set out in it and there are no attempts to impair the impartiality of the expert, there will generally be no waiver of privilege in relation to proper communications with the expert upon tender or service of the expert's report..