A case from 2021, brought to the Supreme Court of Canada further clarifies a patient’s burden of proof in a medical malpractice case.


In 2010, the plaintiff, Karen Armstrong was seriously injured during a colectomy surgery. Armstrong brought an action against Dr. Colin Ward who performed the surgery. A trial judge found Dr. Ward to have been negligent, causing the plaintiff’s injuries.

 The Ontario Court of Appeal

The defendant appealed the finding of liability and the case was then brought to the Ontario Court of Appeals. The court in this case found that the trial judge erred when defining the standard of care which Dr. Ward was required to meet. The standard he was held to initially was one of perfection, meaning the trial judge incorrectly concluded that had the defendant injured the plaintiff with the tool being used, he was liable. When in fact, the judge should have determined if Dr. Ward performed the operation in a way that a reasonable prudent surgeon would have.

 The appeal was allowed and the court reconsidered the case. While they found that the trial judge had erred by holding the doctor to a standard of perfection, the Court of Appeal held that the trial judge was correct in finding that the cause of damage done to the plaintiff was fully supported by the evidence.

 The Supreme Court of Canada

In 2021, the case was brought before the Supreme Court of Canada. McLeish Orlando discusses important findings from the case in an article posted in May 2021. As summarized, the Court considered the standard of care and found that the trial judge’s findings regarding a reasonably competent surgeon were fully supported by evidence. Looking at this evidence, Dr. Ward breached the standard of care.

 Ms. Armstrong then had the burden of proof to establish that Dr. Ward failed in meeting the standard of care that a reasonably competent surgeon would have when her ureter was injured, during the laparoscopic removal of her colon.

 The judge stated that,

“ (135) In this case, the trial judge considered and explicitly rejected the nonnegligent causes put forward by the appellant’s expert witnesses. As I have explained, there was no evidence in this trial to suggest that a reasonably competent surgeon, “trying” to stay at least two millimeters away, might accidentally have injured the ureter during this particular operation. The expert evidence detailed earlier was to the contrary. The trier of fact is required to determine the standard of care and its breach based on the evidence and not on speculation. The onus on a plaintiff in a medical malpractice case is not to disprove every possible theory that might be put forward by a defendant, let alone theories that are not raised at trial, but only on appeal.”

 The decision found in this case reinforces previous case law which allows that a plaintiff in a medical negligence case does not need to disprove every possible theory the defendant may advance. The plaintiff must prove all elements on a balance of probabilities as expecting a patient to be able to specifically explain how a doctor was negligent could create an imbalance as a plaintiff often doesn’t know exactly what occurred during the surgery.

 Find the Supreme Court findings here.

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From CanLii