The Ontario Court Of Appeal Upholds The Use Of "Powerful" Epidemiological Data To Infer Causation In The Absence Of Scientific Certainty

• Law Firm: Bennett Jones LLP
• Subject Matter: Litigation, Mediation & Arbitration, Trials & Appeals & Compensation, Personal Injury, Professional Negligence
• Author: Ms Cheryl Woodin and Alexander Payne
• Published date: 18 May 2023

The Court of Appeal for Ontario in Levac v James, 2023 ONCA 73 [Levac] has unanimously upheld a trial judgment in a common issues trial regarding an infectious disease outbreak in respect of which the allegedly negligent cause was linked to a very high statistical increase in risk, and for which no alternative and non-negligent cause was presented.

The Court of Appeal's decision clarifies the circumstances in which statistical evidence, particularly epidemiological evidence, may be used to infer causation. Epidemiology is the study and analysis of the distribution of patterns and determinants of health and disease conditions in a defined population'it examines associations between health risks and outcomes in a population. The Court of Appeal concluded that where there is (1) a proven breach of the standard of care in negligence; and (2) a proven injury, then "powerful" epidemiological evidence can be used to infer causation, even if it cannot be proven with scientific certainty.

Background and Trial Decision

The treating physician and appellant, Dr. James, was an anesthesiologist who administered epidural injections into the area around his patients' spines as a pain relief treatment. Some of his patients developed meningitis, an acute inflammation of the protective tissue surrounding the spine typically caused by a bacterial or viral infection, or other serious infections, after receiving injections.

A class proceeding was commenced on behalf of a class of patients who developed signs or symptoms clinically compatible with bacterial meningitis, epidural abscess or cellulitis of a bacterial origin and/or bacteremia (collectively, the Injuries) after receiving an epidural injection administered by Dr. James.

The class was divided into subclasses, including (1) patients who were infected by a rare strain of CC59 Staphylococcus aureus bacteria that genetically matched the bacteria that colonized Dr. James himself (the Genetically Linked Patients); and (2) the remaining patients, who suffered Injuries but could not scientifically prove that they were infected by the same rare CC59 strain that colonized Dr. James (the Remaining Patients).

Following a five-week common issues trial, the trial judge, Justice E.M. Morgan, found against the anesthesiologist on all the common issues: negligence (duty of care, standard of care and breach, and causation), fiduciary duty, limitation period and entitlement to punitive damages.

In the context of the negligence analysis...