The counterfactual analysis aspect
A case worth reading, because it accurately explains how the but-for counterfactual hypothetical (i.e., possible, what-if, etc., world) analysis is to be done. (For those who have been paying attention, that’s the analysis for a test that we’ve been told isn’t metaphysical at all, which is one reason why we’re to use it rather than go adventuring with philosophers into abstract metaphysics, or something like that.)
Lee v Minister for Correctional Services,  ZACC 30, 2013 (1) SACR 213 (CC) (11 December 2012) starting at para. 37.
As a colleague put it, the court’s explanation is “far better than anything our Supreme Court has ever come up with”.
One case that isn’t helpful on the “how” of the counterfactual analysis – even if, for other reasons, the result of the case is correct: I make no comment on that point – is Eli Lilly and Company v. Apotex Inc., 2014 FC 1254 at paras. 20-35. I believe that, after you read Lee, if you read Lee, you’ll understand why the discussion in Eli Lilly isn’t helpful. And why the explanation is wrong, even if the conclusion is correct.
The how much evidence is enough aspect – i.e., the Snell robust and pragmatic inference
B.C. lawyers should note that the Ontario Court of Appeal decision in Aristorenas v. Comcare Health Services, 2006 CanLII 33850 (ON CA) leave to appeal to SCC denied 2007 CanLII 10550 (SCC), which also deals with this issue, and is explained in St-Germain c. Benhaim, was applied in Ediger v. Johnston, 2011 BCCA 253 (the SCC reversal, 2013 SCC 18, was on other grounds) and Redmond v. Krider, 2015 BCSC 178. I attempted to explain Aristorenas in my LLM thesis. The QCCA explanation is the better authority.
B.C. lawyers should also note that there continues to be too many trial decisions whose statements of the current meaning of the but-for test, as established by the Supreme Court of Canada, are not worth reading, because they’re wrong (even when the cases cite one or both of Clements and Ediger, which the cases quite often don’t).