Are the “desk studies” of expert doctors reliable opinion evidence?

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Anderson v Yongpairojwong [2023] NSWSC 1359

In this case, the court considered the weight to be given to evidence of expert physicians who had not actually seen a patient, but rather conducted a “desk study” based on documents of other treating physicians.


These proceedings involved a contested probate application concerning two wills executed by the testatrix – one in NSW in 2017 (the “Australian Will”), and another in Thailand in 2020 (the “Thai Will”). The plaintiff (the testatrix’s daughter) sought to have letters of administration with the Australian Will annexed granted to her.

By cross-claim, the second defendant (the testatrix’s son) sought letters of administration with the Thai Will annexed granted to him, or alternatively, an order that probate be granted to the executor of the Thai Will (being the first defendant, the testatrix’s brother).

Despite the Thai Will complying with formal validity requirements, the plaintiff sought to have the validity of the Australian Will upheld. The plaintiff argued that the testatrix did not have testamentary capacity, or knowledge and approval, when executing the Thai Will. The plaintiff claimed that because of the physical and mental effects of various treatments when the testatrix was diagnosed with lung cancer, the testatrix was not of sound mind when the Thai Will was executed.

Expert evidence

The plaintiff relied on the evidence of two medical experts – Dr D, a medical oncologist with a specialisation in advanced lung cancer, and Prof O, a general physician with a specialty in addiction medicine. Neither expert was a treating physician of the testatrix.

Dr D opined that it was highly unlikely that the testatrix had the cognition to understand and appreciate the nature, impact, and effect of the Thai Will. The second defendant submitted that Dr D’s opinion was inadequate because it was based upon his review of limited medical records which documented the testatrix’s treatment and hospital admissions.

Dr D acknowledged that the records were not comprehensive and did not disclose a “day to day” record of observations and treatment, which would have assisted him in being more specific in his observations. The medical records reviewed by Dr D also did not have any notations or observations of any cognitive impairment, or any reference to the testatrix suffering from cognitive side effects of her treatment.

Likewise, Prof O provided an opinion that the testatrix’s cognitive state would have been significantly impaired and diminished. Like Dr D, Prof O was briefed with various medical records, and he observed that the hospital records were not complete.

For example, they did not include ongoing care notes, nursing notes, occupational therapy notes, and registrar’s notes, which Prof O agreed might have been very useful when giving his opinion. As a result of the hospital records being incomplete, Prof O was forced to make various assumptions in preparing the medication summaries. Like Dr D, Prof O agreed that those records might have been very useful.

Prof O accepted that he could not quantify the extent to which the testatrix’s cognition was impaired, and stated that there was no basis on which he could. He candidly acknowledged that the real way of determining what effect illness and its treatment have on a person is by having a conversation with them.

While the court did not doubt the expertise, professionalism, and objectivity of either expert, and although their expert reports were very comprehensive, the court was mindful that the reports were in the nature of desk studies.

Neither expert had seen nor examined the testatrix. Significantly, prior to finalising their expert reports, neither expert was given the benefit of reviewing any of the lay witness statements, nor were they briefed with copies of the various videos which cast light on the testatrix’s physical and cognitive condition at various relevant points in time.

For these reasons, Griffiths AJ accepted the submission of the second defendant that the medical opinions of both Dr D and Prof O, while sincerely given, were largely speculative, based on incomplete medical evidence, and on assumptions drawn from generalisations and not from specific observations in the medical records.

As such, the court did not consider that the opinions of the experts outweighed the evidence of the lay witnesses, and other materials which supported a finding that the testatrix did not lack testamentary capacity. [198]

The court cited Nicholson v Knaggs [2009] VSC 64, where the observations of Vickery J were particularly apposite in this matter:

In the end it is for the Court, assessing the evidence as a whole, to make its determination as to testamentary capacity. In the present case, the opinions of expert witnesses as to whether the testator was competent or not competent, while not without weight, cannot be decisive as to testamentary capacity at the relevant times. The Court must judge the issue from the facts disclosed by the entire body of evidence, including the observations of lay and professional witnesses who knew and saw the testatrix at the time of her making the relevant wills and codicils. The manner in which she gave her instructions, the content of those instructions, the setting in which the instructions were given and the outcome of enquiries made by the solicitor acting in the matter, all assume importance.

The court ordered probate to be granted in solemn form to the first defendant. The plaintiff was ordered to pay the costs of the two expert medical reports.

Key takeaways

  • Experts should be briefed with all relevant materials where those materials are available. Those materials may include the statements of lay witnesses.
  • An expert’s assessment of a patient based on a desktop study, together with assumptions based on generalisations, will impact on the weight to be given to that evidence by the court.
  • The role of the court is to judge the issue before it from the facts disclosed by the entirety of the evidence, both of lay witnesses and expert witnesses. Evidence from an expert that is largely speculative, albeit given sincerely, may ultimately be of little benefit or no benefit to the court.


Read the full decision here.

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