What is the test for drawing an adverse inference of causation against a defendant?

The trier of fact is not required to draw an adverse inference of causation against a defendant. It is a discretionary decision, but it must be based on an evaluation of all of the evidence. See Benhaim v. St-Germain, 2016 SCC 48 at paras. 44 and 52. In deciding whether to draw an inference of causation, a judge is required to take a robust and pragmatic approach to the totality of the evidence, which approach recognizes that precise, scientific proof of causation is unnecessary. In other words, there is a distinction between finding that the plaintiff has failed to meet the burden of proof, which raises a question of fact, and failing to apply a robust and pragmatic approach to the evidence of causation in the proper circumstances, which raises a question of law.