Posing the question of causation to juries in personal injury trials

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The Ontario courts has continuously grappled with defining the test for causation in personal injury cases with multiple defendants.

In Clements v. Clements, 2012 SCC 32, the Supreme Court of Canada affirmed the causation test as: whether “but for” the defendant’s breach of the standard of care, would the plaintiff have suffered some harm? But there has continued to be debate over how this question should be worded, particularly with respect to jury trials.

In 2017, the Ontario Court of Appeal decided in Surujdeo v Melady, 2017 ONCA 41, that “but for” language should be used in jury instructions. However, that same year, the Ontario Court of Appeal heard Sacks v Ross, 2017 ONCA 773, a delayed diagnosis case, and determined that asking whether the breach of the standard of care “caused or contributed” to the harm was embodied in the “but for” test and was therefore appropriate language to use. The Ontario Superior Court has revisited this issue in two recent cases involving multiple defendants: Cheesman v Credit Valley Hospital, 2019 ONSC 4996 and Doobay v Fu, 2020 ONSC 1774.

In Cheesman v Credit Valley Hospital, the plaintiff developed orbital cellulitis, an infection of the inner orbit of the eye. She went to the hospital and, as a result of complications, the plaintiff’s feet and hands were partially amputated. The plaintiff brought an action against the defendant physicians and nurses alleging their negligence caused her complications and ultimately led to her partial amputations.

The parties had differing positions on how the jury question regarding causation should be worded. The plaintiff claimed “caused and contribute” language was appropriate, whereas the defendants submitted that “but for” language was the correct wording.

Justice Koehnen found that “but for” language can cause confusion in cases with multiple defendants. Therefore, in cases where the defendants point the finger at each other, “cause or contribute” language is appropriate.

In this case, the defendant physicians cross-claimed against the nurses and also gave evidence suggesting responsibility against the other defendant physicians. For that reason, the court concluded the case justified the use of “cause or contribute” language over “but for” language.

The court held that the “cause or contribute” language is no different than the “but for” test, it is merely a simpler and clearer way of phrasing the causation question in situations involving multiple defendants.

Although an appeal was initially launched, it has now been resolved and therefore withdrawn. Accordingly, this decision stands.

In Doobay v Fu, the plaintiff experienced symptoms of a stroke and went to the hospital where she was assessed by the defendant doctors and nurses. The plaintiff brought an action against the defendants alleging that they failed to recognize she was suffering from a stroke and thus failed to treat her by way of thrombolytic therapy in a timely manner, resulting in her suffering permanent brain injury.

This was a jury trial, and like Cheesman, the parties debated over the language to be used in the jury questions relating to causation, specifically whether “cause or contribute” language or the “but for” test should be used.

Justice Bale favourably cited the Court of Appeal’s decision in Sacks v Ross, 2017 ONCA 773 in which the Court of Appeal held that the “but for” test was problematic in cases with multiple defendants.

Justice Bale noted that the claims against the individual defendants were not based on discrete factual situations, all of the plaintiff’s injuries were the result of the stroke. For this reason, the use of “but for” language in the causation question would have a significant potential to confuse the jury.  Therefore, Justice Bale held that “cause or contribute” language should be used to translate the “but for” test into everyday language.

These two cases affirm that in cases with multiple defendants, “cause or contribute” language is favoured over the “but for” test for jury questions about causation in order to avoid confusion by using the most normative language possible.

Kristina Maitland is a lawyer with Bogoroch & Associates LLP.