In Pirmax Pty Ltd v Kingspan Insulation Pty Ltd  FCA 1340, the independence of Kingspan’s expert was attacked because of their pre-existing relationship with the company.
Both parties manufacture polyisocyanurate rigid thermal insulation products. Pirmax alleged that Kingspan engaged in misleading and deceptive conduct aimed at damaging its business by way of communications made to the market about the performance Pirmax’s products.
Dr B, a fire safety engineer, had been commissioned by Kingspan in late 2018 to produce a report of his observations when testing the Pirmax products. In that report, Dr B made statements that claims made by Pirmax in technical sheets for the products were false and misleading. That report was referenced and attached to the impugned communications made by Kingspan, which held out Dr B as an independent expert who provided an opinion that was reliable and credible.
Pirmax claimed that by “[d]eploying [Dr B’s] report in the way it did, Kingspan clothed it and the statements and representations within it with the spurious appearance of authority” . Pirmax further claimed that Dr B was not qualified to give an expert opinion that the information contained in Pirmax’s technical data sheets was false and misleading.
Each of the parties led evidence from expert witnesses. Dr B produced four reports and made two affidavits for the purposes of the proceedings.
The day before the trial commenced, Pirmax asserted that Dr B was a “hired gun” for Kingspan and that his report and subsequent evidence aligned with Kingspan’s interests was a result of a lack of independence. Pirmax submitted that Dr B’s evidence was inadmissible under s 79 of the Evidence Act 1995 (Cth) or alternatively, that it ought to be excluded pursuant to s 135.
Pirmax also submitted that aspects of Dr B’s conduct throughout his engagement by Kingspan’s solicitors was inconsistent with the Expert Evidence Practice Note (GPN-EXPT) and the Harmonised Expert Witness Code of Conduct. During the course of proceedings, Dr B was cross-examined in the usual manner.
Citing the observations of Callinan J in Boland v Yates Property Corporation Pty Ltd (1999) 199 CLR 270 at 266-7 that “[f]or … legal advisors to make suggestions is quite different from seeking to have an expert witness given an opinion which is influenced by the exigencies of litigation or is not an honest opinion that he or she holds or is prepared to adopt”, Snaden J found the communications from Kingspan’s solicitors to Dr B did not occasion or establish any lack of independence on his part inconsistent with the Practice Note or Code of Conduct. 
Further, Snaden J found that Dr B’s independence was not improperly or impermissibly compromised because he had produced an earlier report for Kingspan which was the subject of the alleged misleading and deceptive conduct.
Pirmax did not attempt to establish that Dr B’s evidence failed to meet the requirements of s 79 of the Evidence Act.
As to s 135 of the Evidence Act, while the prejudice to Pirmax was obvious, it was not unfair. Even if he was a partial, Dr B’s evidence at trial remained of some significance because it plainly holds at least some probative value.  The fact that Kingspan wanted to make as much as it could of Dr B’s evidence by “weaponising” it was not evidence of a lack of independence on Dr B’s part. 
- Issues of independence of an expert witness go to weight, and not the admissibility, of the expert evidence.
- Engaging an expert who has previously worked with a party in a different capacity may expose the expert to attacks on their credibility and independence.
- A prior relationship with the expert will not necessarily amount to unfair prejudice to the other party which would outweigh the probative value of that expert’s evidence.
Read the full decision here.