Medical causation: the onus of proof and the medico-legal evidence to be considered

By Barbara Casado and Bree Cohen

Insurance Australia Limited t/as NRMA Insurance v Trkulja [2023] NSWSC 956

A recent New South Wales Supreme Court decision provides guidance as to what compulsory third party (CTP) insurers should consider when reviewing adverse medical assessment certificates addressing causation and where medical opinion has been excluded from the review. In this article, we examine the case and its implications.


Brojan Trkulja (Trkulja) was a back-seat passenger in a vehicle that collided with the rear of another vehicle on 3 January 2017 (accident). Trkulja alleged that they suffered physical and psychological injuries and a claim for damages was brought against Insurance Australia Limited t/as NRMA Insurance (Insurer) under the Motor Accidents Compensation Act 1999 (NSW) (MAC Act).[1]

The Insurer initially conceded that Trkulja’s injuries gave rise to a whole person impairment (WPI) of greater than 10% but the concession was withdrawn a few months later.[2] Trkulja lodged an application for assessment of WPI at the Personal Injury Commission (PIC) and was assessed by PIC Medical Assessor Dr Farhan Shahzad (Assessor Shahzad) at 17% WPI.

The Insurer sought review by a medical review panel under section 63 of the MAC Act, which was accepted and allocated to the Review Panel (Review Panel). The Insurer opposed the Review Panel determining the issues without a re-examination and pressed that the Review Panel ‘must conduct its assessment afresh’ due to the inconsistencies in the assessment and the evidence. The Review Panel concluded that a re-examination was not required and that the issue of causation would be dealt with separately.

PIC decision under review

The Review Panel issued a certificate on 9 December 2022[3] affirming the decision of Assessor Shahzad. In coming to their decision, the Review Panel found that:

  • the insurer had ‘failed to persuade the panel that the evidence upon which it relies establishes on the balance of probabilities that the forces involved in the accident were sufficient to cause the [alleged] injuries…’;[4]
  • having reviewed the parties’ respective expert liability reports, ‘the nature of the damage is consistent with the front to rear end collision between the vehicles’ and therefore causation was established;[5] and
  • the Insurer’s medical reports did not comply with clause 1.41 of the Motor Accident Permanent Impairment Guidelines (Guidelines),[6] which provides that a ‘medical assessor’ must provide a claimant an opportunity to address the inconsistencies between the ‘medical assessor’s’ findings and the medical records or observations on non-clinical activities, and on that basis the Review Panel was unable to rely on those reports.

The Insurer disagreed with the Review Panel’s decision and filed a summons seeking judicial review in the Supreme Court of NSW.


The Insurer contended, among other things, that the Review Panel’s decision should be set aside as the Review Panel:[7]  

  1. erred in excluding the Insurer’s medico-legal evidence from its consideration; and
  2. erred in determining causation.


His Honour Justice Chen SC granted the relief sought by the Insurer, namely that the dispute was remitted to the PIC for referral, under section 63 of the MAC Act, to a differently constituted review panel to be determined according to law.

Exclusion of medico-legal evidence

The Insurer succeeded on this point. The exclusion of the Insurer’s medico-legal reports to the Medical Assessor’s and Review Panel’s consideration – on the basis that the medico-legal reports failed to comply with clause 1.41 of the Guidelines and caused procedural unfairness to Trkulja – caused the Review Panel to fall into legal error by misconstruing the MAC Act and misdirecting itself.[8]

His Honour Justice Chen SC noted that both the Medical Assessor and Review Panel accepted Trkulja’s submissions on this point without the required analysis. Further, neither Trkulja nor the Review Panel identified the basis for which medico-legal experts are required to comply with Clause 1.41 of the Guidelines because ‘none exists’.[9]

The Review Panel, which ‘does not have an unfettered discretion’,[10] cannot ‘depart from its duty to apply the general law’.[11] His Honour Justice Chen noted the Guidelines ‘recognise a distinction’ between appointed medical assessors and practitioners that provide medical reports or medico-legal reports,[12] and stated that:

‘…there is no statutory expression requiring a medical practitioner, qualified by a party to give an opinion on, and undertaken an assessment of, permanent impairment to comply with the Guidelines in any respect. Presumably they would do so, at least in the way in which they assessed and expressed any permanent impairment: a report that correctly addressed the requirements of the Guidelines in order to reach an impairment would facilitate clear identification of the degree of any permanent impairment and, further, whether there was likely to be a threshold dispute, or not. But that, of course, is propositionally distinct from mandating that they do so, with the consequence that the use of the report is precluded absence that compliance. And it is propositionally distinct from requiring that they comply with all the provisions within the Guidelines, with the consequence that the use of the report is precluded absent that compliance.’[13]

The suggestion that the Insurer, by not challenging Trkulja’s submissions regarding the Guidelines inferred concession on the issue, was not accepted. As the Review Panel was required to address a legal issue, it was incumbent upon it – even if no submissions were made – to satisfy itself that Trkulja’s submissions were correct.[14] The Review Panel was required to discharge that duty.

The Insurer submitted that it was open to the Review Panel, accepting non-compliance with the Guidelines, could have given the medico-legal reports little or no weight, but His Honour Justice Chen disagreed as the Guidelines had no application in the medico-legal context.[15]


The Insurer contended that the Review Panel erred by incorrectly reversing the onus of proof, confining its consideration of the causation issue, and failing to make findings in connection with causation.

His Honour Justice Chen agreed that the Review Panel reversed the onus of proof, as the Review Panel stated within its reasons that the Insurer did not establish causation even though it should have been upon Trkulja to do so.[16] Further, there was no dispositive finding leading to the causation conclusion, no clear and correct legal direction, and no reference to section 5E of the Civil Liability Act 2002 (NSW) which identifies who bears the onus of proof.[17] The Review Panel was found to have, by this misdirection, misstated the legal test and committed an error of law.[18]

Further, as to whether the Review Panel incorrectly confined its consideration of causation, his Honour Justice Chen stated that:

‘the function of the medical assessor (and, necessarily, the review panel), to whom a dispute has been referred, is to assess the degree of permanent impairment as a result of the injury caused by the motor accident… It follows that, to do otherwise and confine the enquiry to a sub-issue within that dispute would be to contravene the statutory directive. That is what occurred here.’[19]

As the Review Panel dealt with only a confined issue on causation, namely the cause of the accident rather than whether the injuries were caused as a result of the accident, the Review Panel did not address the medical dispute and therefore fell into legal error.[20]

His Honour Justice Chen, noting the above, considered it unnecessary to address whether the Review Panel failed to make findings in connection with causation.

Implications for CTP insurers

This case applies to medical disputes under both the MAC Act and the Motor Accident Injuries Act 2017 (NSW) and provides guidance as to what CTP insurers should consider when reviewing adverse medical assessment certificates (whether on WPI or treatment).

If medical assessors and review panels have excluded from consideration or discounted the weight to be given to medico-legal opinion on the basis that the report does not comply with the Guidelines, or have confined the consideration of causation, there will likely be grounds to seek relief.

CTP insurers should prepare and lodge submissions addressing all issues in dispute to ensure that there is no implied concession. However, in some circumstances – where there is a legal issue for determination – silence should not be taken as concession on the issue and the review panel’s duty to construe the instruments on which the decision is made must still be discharged.

[1] The Insurer was the CTP insurer of the vehicle Trkulja was a passenger of and liability was admitted (see Insurance Australia Limited t/as NRMA Insurance v Trkulja [2022] NSWPICMP 533 at [1] and [4]) Insurance Australia Limited t/as NRMA Insurance v Trkulja [2022] NSWPICMP 533 at [5].
[2] Insurance Australia Limited t/as NRMA v Trkulja [2023] NSWSC 956 at [20].
[3] Insurance Australia Limited t/as NRMA Insurance v Trkulja [2022] NSWPICMP.
[4] n 3 at [51].
[5] n 3 at [50].
[6] n 3 at [30] to [32].
[7] n 2 at [24].
[8] n 2 at [39].
[9] n 2 at [53].
[10] n 2 at [40].
[11] n 2 at [42].
[12] n 2 at [60].
[13] n 2 at [54].
[14] n 2 at [64].
[15] n 2 at [66].
[16] n 2 [83] to [84].
[17] n 2 at [84].
[18] n 2 at [85].
[19] n 2 at [87].
[20] n 2 at [88].


Barbara Casado

Barbara works with insurers to resolve CTP and liability claims. She is an Accredited Specialist in Personal Injury Law.

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