Health Law Blog

Expert witnesses must not be partisan or argumentative

August 10, 2021

Expert witnesses play a crucial role in medical negligence cases. Proof of that is shown in a recent dismissal of an appeal by a gynecologist after a trial court found that his breach of the applicable standard of care resulted in a patient's death.

In Hacopian-Armen Estate v. Mahmoud, a patient was referred to a gynecologist in 2009 after she was diagnosed with fibroids - benign, non-cancerous growths - and was experiencing heavy bleeding with clots during her menstrual periods. While the patient showed risk factors for diseases of the uterus, the gynecologist did not perform an endometrial biopsy during the medical examination, though it is a simple procedure that could have been done in a few minutes in the doctor's office.

According to court documents, the patient continued to suffer from ailments including deep vein thrombosis and pulmonary nodules. In April 2011, the gynecologist conducted an endometrial biopsy, revealing a high-grade cancerous tumour in her uterus. The woman underwent treatment but died months later of uterine leiomyosarcoma (uLMS), which had metastasized to her lungs.

Her family members filed a medical negligence action alleging an endometrial biopsy in 2009 may have detected the cancer sooner, allowing for earlier treatment.

In accepting the evidence of the family's two expert witnesses while rejecting the evidence given by the gynecologist's trio of expert witnesses, the trial judge determined the doctor breached the required standard of care when he failed to perform an endometrial biopsy in 2009, and awarded the family $300,000 in damages.

On appeal, the gynecologist did not dispute breaching the standard of care but argued there were "several errors in the trial judge's analysis and conclusions on legal and factual causation." The Ontario Court of Appeal rejected that argument, laying out in detail why Justice Carole J. Brown was correct in her decision to conclude that medical negligence led to the woman's death.

It comes down to the credibility of expert witnesses, all gynecologists in this case. The appeal court notes that while the trial judge found all the experts were "well qualified in their fields," the two medical experts for the family were "forthright, impartial and consistent" and their testimony was considered to be credible.

On the other hand, the physicians testifying for the gynecologist gave "evidence in cross-examination [that] contradicted their evidence-in-chief, they were less than forthright in cross-examination and were argumentative," court documents state.

As Justice Brown noted: "Based on the evidence, the medical records, the agreed statements of fact, the reports and testimony of the experts, where there is a discrepancy between the testimony of the plaintiff's experts and the testimony of the defendant's experts, I prefer the evidence of the plaintiff's experts."

In addressing whether the woman's death was foreseeable and connected to the gynecologist's failure to perform an endometrial biopsy in 2009, she found that the risk of uLMS was real, and that it was not something that a "reasonable, skilled, specialist would have brushed aside as far-fetched." She also concluded that it was foreseeable that the presence of uLMS, if not treated, would likely result in serious injury or death.

The appeal court rejected the gynecologist's submission that Justice Brown's approach to foreseeability would require physicians to order unnecessary tests.

"The evidence accepted by the trial judge was that in the circumstances that presented themselves to the appellant on May 25, 2009, an endometrial biopsy was a necessary test and one that should have been performed by a competent gynecologist," court documents read.

The court of appeal judgment also offered this general advice guidance about the relationship between the appeal and trial courts when it comes to assessing evidence. "In an appeal that is largely fact-based, the trial judge's assessment of the frequently conflicting evidence of experts is entitled to deference in the absence of palpable and overriding error," court documents state.

To further justify that deference, the judgment references a 2002 Supreme Court of Canada decision that reads: "A finding of negligence by a trial judge involves applying a legal standard to a set of facts, and thus is a question of mixed fact and law. Matters of mixed fact and law lie along a spectrum ... appellate courts must be cautious in finding that a trial judge erred in law in his or her determination of negligence, as it is often difficult to extricate the legal questions from the factual ... the general rule is that, where the issue on appeal involves the trial judge's interpretation of the evidence as a whole, it should not be overturned absent palpable and overriding error."

This decision shows how important it is to have non-partisan and credible expert witnesses in medical negligence cases on both sides. Partisan experts are decidedly unhelpful on either side of the debate.


Several years ago I was fortunate enough to have been selected as a Tremayne-Lloyd Fellow here at Western Law. I used the funds to finish a book and to begin work on a new one. It dawned on me far too late that I had never thanked you for that splendid gift. The new book is to be published by Harvard Press in 2010. The TTL Fellowships provided ritual seed capital for this project, which required me to spend a good deal of time and money at The National Archive in Washington. Again, with many thanks.

R. W. Kostal Professor of Law and History

Tracey Tremayne-Lloyd Health Law