Back To The Future Causation Alert: Clusters Trumps Medical Causation In Judicial Review Of Technicians' Breast Cancer

Michael J. Fox is a well-known Canadian comedic actor probably best known for the "Back to the Future" movie trilogy and other successful small screen comedies. In medical circles, he is also known for having Parkinson's disease and as a spokesperson for Parkinson's disease research. But Michael's Parkinson's is a little different. He was a member of a British Columbia production crew in the 1970's. Several of that crew went on to develop Parkinsons at a young age. The statistical probability of a number of persons, or a cluster, in the one production crew developing Parkinson's was very small. Clusters "suggest" an environmental agent at work - whether it is scientifically provable or not.

In British Columbia (Workers' Compensation Appeal Tribunal) v. Fraser Health Authority, [2016] SCC 25 (hereinafter "WCAT 2016") the Supreme Court of Canada was asked to look at causation in the context of a cluster of seven British Columbia medical technicians who developed breast cancer while working at the same hospital laboratory. Three of the seven workers applied for worker compensation benefits.

A Compensation review officer denied the claim for benefits. Medical experts who reviewed the case had concluded there was insufficient evidence to sufficiently link breast cancer to laboratory work. The workers appealed to the Workers' Compensation Appeal Tribunal and it found that the breast cancers were occupationally caused diseases in this case. The employer then applied for judicial review and the Workers' Compensation Appeal Tribunal decision was overturned. An appeal to the British Columbia Court of Appeal by the 3 workers was not successful. The workers appealed to the Supreme Court of Canada (the "Court").

In a split decision of the Court, the majority highlighted the distinction between causation under workers' compensation law and causation under tort law. Under workers' compensation law where evidence is evenly weighted on causation, causation is resolved in the workers' favour. Under tort law, evenly weighted causation evidence results in failure of a worker or plaintiff's claim. However, the Court also noted that the 'causation' distinction was not determinative in this case.

The majority stated at paragraph 33 that the Courts below had fundamentally misapprehended how causation, "irrespective of...