District Court confirms common law principles governing admissibility of expert evidence are relevant considerations in WorkCover proceedings

By Rosena De Freitas

The District Court of Western Australia has dismissed an employer’s appeal about the manner in which an arbitrator dealt with expert evidence in WorkCover proceedings, where the rules of evidence do not apply.

Mr Armet injured his back unloading a container while working for CFC Consolidated Pty Ltd on 18 March 2015. Mr Armet returned to work on light duties less than a week later. Around six months after that, Mr Armet aggravated the injury in the same job, which resulted in total incapacity for work. CFC’s insurer accepted liability for the claim.

Mr Armet then alleged that ongoing symptoms of pain due to his compensable back injury had caused a secondary psychiatric condition, being an Adjustment Disorder. The employer disputed this and the dispute went to arbitration. The Arbitrator determined liability for the psychiatric injury in favour of Mr Armet.

The employer appealed the decision, raising three questions of law, concerning the principles governing expert evidence in the context of a WorkCover Arbitration, whether the Arbitrator made findings of fact that were not supported by evidence and whether the Arbitrator’s findings of fact were material to the questions to be determined by him.

Her Honour Judge Wallace noted that, while the rules of evidence do not have strict application in the WorkCover jurisdiction pursuant to section 188(2)(a) of the Workers’ Compensation and Injury Management Act 1981 (WA) (Act), the principles underpinning those rules remain persuasive and are an important guide or tool to assist in the assessment of the reliability, probative value and weight to be given to expert evidence.

This position is consistent with section 188(2)(b) of the Act that the arbitrator is to act according to equity, good conscience and the substantial merits of the case. Her Honour considered that deciding what weight should be given to expert evidence is a factual determination, and so an error of law will therefore only arise if the arbitrator makes a finding of fact in the complete absence of evidence.

In this case, the employer submitted that the diagnoses of the two medical experts were based on facts and symptoms described by Mr Armet that were not proven at Arbitration. On her Honour’s assessment of the evidence before the Arbitrator, her Honour found that the Arbitrator accepted the evidence given by Mr Armet as credible in relation to his symptoms. As such, Her Honour found there was no error of law.

Her Honour found that the role of the Arbitrator was to examine any material variation between the facts as found and the facts relied upon by the expert to determine whether any unproven facts relied upon by the experts rendered the opinion ‘inadmissible or of no or lesser weight and probative value’. Her Honour also considered that giving weight to an opinion in which a number of foundational facts were proven, even though others were not, ‘merely required an assessment of weight to be made by the learned Arbitrator, which does not raise an error of law. At most it may lead to a wrongful or doubtful finding of fact’.

Her Honour found that a discrepancy in and of itself between the facts as proven and the facts assumed by the expert medical practitioner does not inevitably lead to a position that the opinion of the medical practitioner should be afforded no weight.

This decision reaffirms the well-established principles which underlie the task of assessing expert evidence in the WorkCover jurisdiction since the Court of Appeal’s decision in Beer v Duracraft Pty Ltd [2004] WASCA 192. It is a reminder of the need to compare the facts that are proven on the evidence with the facts relied upon by experts to assess the weight to be afforded to the expert’s opinion.

The case is CFC Consolidated Pty Ltd v Armet [2020] WADC 85.