Disley v Mount Emerald Wind Farm Pty Ltd & Anor (No 2) [2022] QSC 54

Julie Whitehead   |  Luke Trimarchi  |  Alisha McGrady

Key takeout

The general principle of expert evidence is that, without compromising the interests of justice, evidence on one issue should be addressed by a single expert.  Where there are multiple experts, each expert should be clearly informed of the issues to be addressed in order to avoid overlapping evidence and encroachment

Facts

Jennifer Disley (Disley) commenced proceedings against Mount Emerald Wind Farm Pty Ltd (MEWF) and Marshall Day Acoustics (Marshall) in relation to the effects of noise from a wind farm, located 1.87 kilometres from Disley’s rural property. Disley advanced various allegations, including that the noise generated by the wind farm, operated by MEWF, exceeded the limits of the relevant development approval and therefore interfered with Disley’s use and enjoyment her property.  Prior to construction of the wind farm, Marshall was engaged to assess and predict the impact of the wind farm and the level of noise it would generate.  Marshall prepared five reports. Disley contended Marshall was also liable for the alleged nuisance caused by the wind farm because its reports were used by MEWF to secure the relevant development permit.  Disley argued that Marshall’s reports were defective and pleaded cases against Marshall in negligence, negligent misstatement and misleading and deceptive conduct.

Disley called two experts witnesses to give opinions on the same issue of standardised audio measures and assessments.  MEWF and Marshall applied to stop Disley calling more than one expert on the same issue, arguing that it was contrary to the general principle that, without compromising the interests of justice, evidence on a particular issue should be given by a single expert.

The court agreed and ordered under r 367(3)(e) of the Uniform Civil Procedure Rules 1999 (Qld) that Dinsely should notify MEWF and Marshall which expert she intended to rely on at trial or alternatively, of her intention to have the two experts provide evidence on separate issues.  Disley notified of her intention to have the experts address separate issues, however, upon receiving the revised reports, MEWF and Marshall maintained that the reports spoke to the same issues.

Decision

Henry J agreed with MEWF and Marshall that the expert reports were deficient as they addressed overlapping issues and ordered that Disley serve a third revision of the reports ensuring the experts addressed separate issues.

The court outlined the following deficiencies of the revised reports:

• each expert referred to the content of an earlier report and did not produce a standalone document;
• Disley’s legal representatives should have distilled pleadings into a practical list of factual issues to be addressed by each expert to avoid duplication of evidence;
• each expert should have been informed of the issues to be addressed by the other to avoid encroachment;
• while the questions appeared cosmetically different, many assigned to each expert went to the same topic; and
• the list of questions did not correlate to issues of fact arising from the pleadings.

While each expert was supposedly confined to separate issues, Henry J noted that there was significant overlap.   The experts similarly addressed measurement of objective noise levels, the subjective experience of noise by Disley, Marshall’s noise predictions and commented on compliance reports produced by Marshall.  The court held that this was likely a result of the reliance by the first expert on raw data collected and interpreted by the second.  While it is permissible for another expert’s data to be incorporated as an appendix to a report, it is not appropriate for that expert to provide an opinion on data they did not collect.

Henry J acknowledged that Disley would have incurred significant expense to serve the revised reports, however, it was Disley’s decision to proceed with two experts and provide overlapping evidence.  Disley was ordered to serve further revised reports addressing separate issues in the proceedings.  In the orders, Henry J included a liberty to apply clause allowing the Disley to request the court’s directions as to the appropriateness of a proposed list of issues to be addressed by each expert.  Henry J advised Disley to first consult MEWF and Marshall and seek their agreement with the list of issues to avoid the unnecessary cost of a further court appearance.