In Sacks v. Ross, the Ontario Court of Appeal dealt with how to apply the causation test in medical negligence cases involving multiple tortfeasors.

Sacks suffered serious injuries arising from complications after a routine bowel surgery. An anastomotic leak occurred after surgery, which spilled into his abdominal cavity, but the discovery of the leak was delayed, and by the time treatment started, he was in septic shock. Ultimately, he was in a coma for several weeks and his legs were both amputated.

At trial, Sacks put forth that the delay and treatment caused his injuries, which were the result of cumulative errors made by the respondents, a team of doctors, nurses and Sunnybrook Hospital, who treated him after his bowel surgery. The respondents argued that the delay in diagnosis did not cause Sacks’ injuries – his injuries were actually caused by flesh eating disease, which could not have been diagnosed or treated when it first arose.

At trial, the jury found five of the defendants breached their respective standards of care, but none of the breaches caused the injuries. Sacks appealed, arguing that the trial proceeded on a mistaken understanding of the appropriate causation test, evidenced by improper jury questions and instructions. Sacks argued that in cases involving multiple tortfeasors, a “global but for” test for causation should apply.

Ultimately, the Ontario Court of Appeal dismissed the appeal. The Court followed the prior Clements decision, where the Supreme Court found that the “but for” test also applies in complex, multiple tortfeasor, negligence cases.

The Sacks decision is significant for the Court’s discussion of the causation test and how it should be applied in complex negligence cases. The Court reminded that the normal causal reasoning process follows three steps:

Step one: what likely happened in actuality – whether the delay in treatment led to the plaintiff’s injury?

Step two: what would have happened if the defendant had not breached their standard of care?

Step three: allocate fault amount the negligent defendants

The analysis requires the jury to analyze each event in the sequence of events, while ignoring any decision it might have made with respect to an earlier event.

To reflect the causal reasoning process, the court recommended framing the jury questions as follows:

  1. Have the Plaintiffs proven, on a balance of probabilities, that a delay in treatment caused Sack’s injuries?
  2. If yes to #1, have the Plaintiffs proven, on a balance of probabilities, that the delay resulting from [this defendant’s] breach of the standard of care caused or contributed to the injuries of Sacks?
  3. If yes to #2, how did [this defendant] breach the standard of care?

Importantly, question #1 only asks the trier of fact to consider what the plaintiff needed by way of timely diagnosis and treatment in order to avoid injury, without considering the presence or absence of any breaches of the standard of care. In contract, question #2 determines fault.

See Sacks v. Ross, 2017 ONCA 773 (CanLII)