The Supreme Court of Canada’s recent decision in Clements v. Clements has two main take-home messages for tort law practitioners.

First, ‘material contribution to risk’, as it should now be known, is an exceptional doctrine whose application will only be appropriate where a plaintiff can establish causation globally against several tortfeasors, but cannot identify which of them was in fact the ‘but for’ cause of her injury. In this situation, each defendant put the plaintiff at risk, and the only reason none of them can be identified as a ‘but for’ cause of the injury is the fact that they can all ‘point the finger’ at each other. To put it colloquially, material contribution is appropriate where the question is ‘whodunnit’?

Second, Snell v. Farrell is back in vogue. The ‘common sense’, ‘robust and pragmatic approach’ is not a test or a doctrine that applies only in certain cases – it is the approach to take in ‘but for’ causation. The ‘but for’ test does not demand scientific proof of causation. Causation can be proved by inferences drawn from circumstantial evidence, and the causal inquiry must be informed by common sense.

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