Standard of Care and Causation in Medical Malpractice Class Actions

A Case brought before the Ontario Court of Appeal demonstrates how issues of causation and standard of care are handled in class action medical malpractice cases. 


In 2022, the Ontario Court of Appeal heard an appeal regarding a class action lawsuit resulting from an infectious disease outbreak in Toronto at the Rothbart Centre for Pain Care Ltd. After an extensive investigation, the outbreak was found to have been caused by inadequate practices and procedures intended to prevent or reduce such infections.

The rate of the infection associated with the epidural injection administered by Dr. Stephen James, an anesthesiologist, was much greater than the general risk for such a procedure. James was also found to be colonized with a rare strain of bacteria matching the same bacteria found in six patients. Those infected with the strain were in a subclass of the plaintiff class called the “Genetically Linked Patients”.

The trial judge found against James on all the common issues and concluded that he had breached the standard of care for all injections he performed during the class period by not employing an aseptic technique consistently for the injections.

The judge concluded that causation was proven for the Genetically Linked Patients on the basis of the genetic match between the bacterial strains and the expert evidence on the lack of viable explanation for the genetic match.

For the remainder of the class, expert evidence regarding the correlation between faulty IPAC and high infection rates was considered. The trial judge also considered statistics evidence that James had a 49-69 times greater risk of serious infection when compared with the accepted risk of infection with such injections. The judge ultimately concluded that each member must establish that they likely were infected because of Dr. James’ breaches.

The Court of Appeal

James appealed this decision arguing that the trial judge erred in finding that he breached the standard of care. He also alleged that the trial judge erred in finding his breaches of the standard of care to have caused the injuries of the plaintiffs. The appellant argued that the trial judge’s finding that James breached the standard of care by not using an aseptic technique could not be grounds for liability in negligence for the entire class because of the unique interactions between James and each patient.

The Court of Appeal held that:

…It was open to the trial judge, relying on the expert evidence, the evidence of nurses who worked with Dr. James, and Dr. James’ own evidence, to conclude that he breached the applicable standard of care by not consistently using an aseptic technique.

IPAC is akin to a systemic policy or practice that is intended to be applied consistently. The fact that there may have been some variation in individual experience does not preclude answering the question in common given the finding that an aseptic technique was always required.

Dr. James’ failure to adhere to the required IPAC standards in all cases exposed his patients to a common risk of harm. Whether this breach led to the infections is a question for the causation analysis. Direct evidence from every Class Member was not required where the plaintiff’s theory…”

As for the issue of causation, the appellant argued that only patient-specific evidence, not considered by the trial judge could have lead to any conclusion that James’ breach of IPAC was the cause of the infection. The Court did not find any error in the trial judge’s finding of causation to the Genetically Linked Patients.

In regards to the remaining class members, James relied on a variety of cases which advised caution in using statistical evidence to establish causation. He argued that the dangers were worsened because the statistical evidence was relied upon to infer causation for the entire class. The Court of Appeal again agreed with the trial judge, stating that correlation is not scientific causation and that scientific certainty isn’t required to establish legal causation.

Further, the Court asserted that trial judges are owed deference when drawing inferences of causation on the basis of statistics. This is outline by the Supreme Court of Canada in Benhaim v. St. Germain, 2016 SCC 48 at para 78:

”Drawing an inference from a general statistic in a particular case is an inherent, and often implicit, part of the fact-finding process. A statistic alone reveals nothing about a particular case. It must be interpreted in light of the whole of the evidence. This interpretation is the role of the trial judge, and it is entitled to considerable deference on appeal…”

The Court held that the circumstancial evidence was powerful enough to conclude a statistic association was representative of a casual link on a balance of probabilities, meaning James failed to provide a non-negligent explanation for the outbreak as a whole.

Read the full case here or find a case summary at Rogers Partner LLP.

MedMalDoctors has a network of medical experts that provides lawyers with opinions on Causation and Standard of Care regarding potential medical malpractice.

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From CanLii