New Causation Test for Occupational Disease: British Columbia (Workers' Compensation Appeal Tribunal) v. Fraser Health Authority, 2016 SCC 25

  • October 21, 2016
  • Stephen C. Roberts

In June of this year the Supreme Court of Canada (SCC) clarified the standard of proof for causation in occupational disease claims in the case British Columbia (Workers’ Compensation Appeal Tribunal) v. Fraser Health Authority (the Fraser Case). It is rare that a worker’s compensation case makes its way to the Supreme Court of Canada so it is important for all working in this area to be familiar with the SCC’s findings.

The Fraser case dealt with seven technicians at a single laboratory who were diagnosed with breast cancer and applied for compensation under the Workers Compensation Act (WCA) in British Columbia asserting that their breast cancer was an occupational disease. The WCA requires that there must be positive evidence of a causal link between the workers’ employment and their breast cancer for the occupational disease to be allowed. The causal link must be a significant contributing factor and therefore must be more than trivial or insignificant. The WCA also provides that if the evidence in the workers’ case is evenly weighted as to causation, the case must be resolved in the workers’ favour (i.e. the benefit of doubt goes to the worker).

In the Fraser Case, there was a statistically significant cluster of breast cancer in the laboratory about eight times higher than expected in the normal population. However, three expert reports submitted to the British Columbia Workers’ Compensation Board (BCWCB) shared the conclusion that there was an insufficient scientific basis to causally link the incidence of breast cancer to the workers’ employment.  Therefore, the BCWCB denied the claims and the workers appealed to the BC Workers Compensation Administrative Tribunal (the Tribunal). Despite the experts’ findings the Tribunal found that there was sufficient evidence to find causation and awarded compensation to the workers.

The Tribunal relied on its ability to draw a common sense inference of causation in the absence of scientific proof rather than requiring a positive link between the disease and employment. The Tribunal found that there was no need to identify a specific causal agent and it was sufficient for the evidence to point to a causal link through strength of association and a temporal relationship.  They concluded that the significant cluster of breast cancer in the laboratory was positive evidence supporting the conclusion that it was likely as not that the workers' cancer was caused by workplace exposure. The employer, Fraser Health Authority then applied to the BC Supreme Court for judicial review of the Tribunal’s decision.

The British Columbia Supreme Court and the British Columbia Court of Appeals both disagreed with the Tribunals decision. The BC Courts asserted that the Tribunal was not entitled to ignore the expert evidence in favour of their own conclusions. This error was equal to patent unreasonableness. The BC Court of Appeal decided that to prove causation in occupational disease cases the Tribunal required evidence beyond a statistical anomaly. The workers and the Tribunal appealed the BC Court of Appeal decision to the SCC and the SCC disagreed with the BC Court of Appeal decision.

The SCC upheld patent unreasonableness as the standard of review and found that the Tribunal’s conclusion that the workers’ cancer was an occupational disease caused by the nature of their employment was not patently unreasonable. The SCC found that the finding of causation is a finding on a question of fact and therefore entitled to deference by the courts. Patent unreasonableness prevents a reweighing of the evidence and is not established where the reviewing court considered the evidence to be insufficient or rejects the inferences drawn by the trier of fact from that evidence. The BC statute specifically contemplates a situation where the evidence is evenly weighted on causation and asserts that the issue must be resolved in the workers’ favour. The SCC found that the idea behind this standard of proof is that workers should obtain compensation without having to satisfy the requirement of a civil tort claim. This standard of proof is not the same as the scientific standard, which requires certainty, and is used by experts in preparing their reports.

The SCC found that the central problem in analysing causation by the lower court was not their failure to acknowledge the less stringent standard of proof but a fundamental misunderstanding of how causation may be inferred from the evidence under this lower standard. The SCC found that in the face of inconclusive or even contrary expert evidence the trier of fact may make inferences as to causation without making a patently unreasonable decision.  The SCC found that there was sufficient evidence in this case to infer causation and therefore upheld the original decision of the Tribunal.

Worker representatives were very concerned that if the BC Courts decisions were upheld that it would be more difficult to prove causation in occupational disease cases. They were concerned that if scientific certainty was required to show positive evidence of a causal link that this would increase the evidentiary burden on workers and result in fewer allowed claims. The SCC has made it clear now that this will not be required. Furthermore, this SCC decision makes a strong endorsement of the strength of curial deference that must be provided to tribunals (where the provincial Act provides for this) and clarifies what the SCC feels is patently unreasonable. Clearly, the SCC is saying that a tribunal can ignore numerous expert reports (including the worker’s own expert and the independent WCB expert) and rely on circumstantial and weaker evidence in reaching a decision and this will not be considered patently unreasonable.

In summary, this decision is going to make it easier for workers to get entitlement in occupational disease cases. In addition, it will make it harder for employers to argue against entitlement in occupational disease cases even if they have expert reports that support their position. Furthermore, this decision may also weaken the causation test in deciding entitlement in other workers’ compensation cases. However, this decision will ensure that most, if not all, tribunal decisions will be upheld on judicial review as the test to show that a decision is “patently unreasonable” just got a lot harder. A review of this SCC decision and its comments on these issue would be recommended.

About the Author

Prepared by Stephen Roberts of the McTague Law Firm LLP. Mr. Roberts represents employers only on Workplace Safety and Insurance and other employment related matters. He has been certified by the Law Society of Upper Canada as a Specialist in Workplace Safety and Insurance Law and is a member of the Executive of the Ontario Bar Association’s Workers’ Compensation Section.

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