Workers’ compensation tribunals have broad ability to weigh evidence

David Marchione

On June 24, a majority decision of the Supreme Court of Canada allowed workers’ compensation claims for breast cancer as related to the workers’ employment in a medical laboratory. The decision relates to workers’ compensation claims that were started at WorkSafeBC about 15 years prior. The decision shines light on the standard of proof to be considered when determining entitlement in workers’ compensation claims.


Three female workers in British Columbia had applied to WorkSafeBC for benefits relating to diagnoses of breast cancer. The workers all claimed  they had occupational diseases under the workers’ compensation legislation as their illnesses arose out of and in the course of their employment. Evidence was submitted from the now defunct Occupational Health and Safety Agency for Healthcare (OHSAH) that found the laboratory where the workers were working was a cancer cluster — an area where contracting cancer was more likely. There was some evidence the technicians were exposed to carcinogenic chemicals and there was a “statistically significant cluster” of breast cancer cases at the lab — eight times the rate that would have been expected in the general population. Despite this, the OHSAH did not reach scientific conclusions to support an association between work-related exposures and breast cancer in the cluster of workers studied.


The workers’ claims were denied by the workers’ compensation board on the basis that there was no evidence their cancer was caused by their work or workplace. This decision was appealed to the B.C. Workers’ Compensation Appeals Tribunal (WCAT) which overturned the board’s decisions and allowed the workers’ claims. The employer requested a reconsideration of the WCAT’s decision and the decision was upheld. The employer then requested that the decision be judicially reviewed on the basis that the decision was “patently unreasonable.” The B.C. Supreme Court agreed with the employer and set aside the tribunal’s decisions. 


Generally, entitlement in workers’ compensation claims is based on the evidence before the decision-maker for a particular claim, based on a particular set of circumstances. The decision-maker, whether it is at the board level or at an appeal, generally makes a determination based on the evidence. Entitlement is granted if, on a balance of probabilities, it is shown that it is more likely than not that the worker’s injury or illness was caused by the work or workplace, or if the work or workplace was a significant contributing factor to the onset of the injury or illness.  Generally, it is a premise in workers’ compensation legislation that if the evidence is equal both for and against a worker’s claim for entitlement, then the entitlement would be granted.


In reaching its decision, the Supreme Court of Canada confirmed that the appeals tribunal has exclusive jurisdiction to hear and determine all questions of fact put before it in a workers’ compensation appeal, and that it has tremendous latitude when doing so. The tribunal’s authority and jurisdiction are confirmed in the workers’ compensation legislation. When deciding questions of fact, the tribunal has the ability to “choose to draw from the expert evidence before it (as it drew here from expert evidence of historical exposures and of a statistically significant cluster of breast cancer cases among laboratory workers). In the decision, the Supreme Court stated “the presence or absence of opinion evidence from an expert positing (or refuting) a causal link is not, therefore, determinative of causation.” It said it is up to the trier of fact to consider all evidence when making a determination about whether the evidence supported an inference that a worker’s condition arose out of and in the course of employment.


The Supreme Court also noted that causation could be inferred, even in the “face of inconclusive or contrary expert evidence — from other evidence, including merely substantial evidence.”


The court was careful to note that this does not mean that evidence of relevant historical exposures would always suffice to support a finding that a worker’s breast cancer was caused by an occupational disease. However, it was noted that it may suffice. Again, the decision would lay with the trier of fact based on the facts and circumstances of the particular case.


Entitlement to workers’ compensation benefits for cancer is treated differently among workers’ compensation legislation across Canada and depends on a number of factors, including the type of cancer and the worker’s occupation. A number of provinces, including B.C., Alberta, Saskatchewan, Manitoba, Ontario and Nova Scotia have presumptive legislation for dealing with entitlement to cancer for occupations such as firefighters. Where such presumptions exist, if a worker is diagnosed with a type of cancer covered by the legislation and worked in a listed occupation, his condition is presumed to have arisen out of and in the course of employment and benefits will be allowed. Where such presumptions do not exist, such as in the case of the laboratory workers in B.C., the evidence must support that it is more likely than not that a worker’s condition arose out of and in the course of employment.


Although one might infer that the Supreme Court’s decision might lead to more workers claiming for and receiving entitlement to cancer they believe resulted from their work, it is important to remember that decisions on entitlement are based on the merits of each individual case. Employers should ensure they keep accurate records of workplace exposures, control programs, hazard assessments, industrial hygiene testing and associated results, in order to be able to put forward a strong position if such claims are made.


This article originally appeared in the October/November 2016 issue of COS.