If leave is granted, the Court might clarify the meaning of the Snell proposition that factual causation is a matter of common sense.
Addendum Feb 1, 2014: Leave to appeal was denied on Jan 30, 2014.
Readers interested in the subject will recall the SCC’s last restatements of the mantra in Clements v. Clements, 2012 SCC 32:
 The “but for” causation test must be applied in a robust common sense fashion. There is no need for scientific evidence of the precise contribution the defendant’s negligence made to the injury. See Wilsher v. Essex Area Health Authority,  A.C. 1074 (H.L.), at p. 1090, per Lord Bridge; Snell v. Farrell, 1990 CanLII 70 (SCC),  2 S.C.R. 311.
 A common sense inference of “but for” causation from proof of negligence usually flows without difficulty. Evidence connecting the breach of duty to the injury suffered may permit the judge, depending on the circumstances, to infer that the defendant’s negligence probably caused the loss. See also the discussion on this issue by the Australian courts: Betts v. Whittingslowe (1945), 71 C.L.R. 637 (H.C.), at p. 649; Bennett v. Minister of Community Welfare (1992), 176 C.L.R. 408 (H.C.), at pp. 415-16; Flounders v. Millar,  NSWCA 238, 49 M.V.R. 53; Roads and Traffic Authority v. Royal,  HCA 19, 245 A.L.R. 653, at paras. 137-44.
 Where “but for” causation is established by inference only, it is open to the defendant to argue or call evidence that the accident would have happened without the defendant’s negligence, i.e. that the negligence was not a necessary cause of the injury, which was, in any event, inevitable. As Sopinka J. put it in Snell, at p. 330:
The legal or ultimate burden remains with the plaintiff, but in the absence of evidence to the contrary adduced by the defendant, an inference of causation may be drawn although positive or scientific proof of causation has not been adduced. If some evidence to the contrary is adduced by the defendant, the trial judge is entitled to take account of Lord Mansfield’s famous precept [that “all evidence is to be weighed according to the proof which it was in the power of one side to have produced, and in the power of the other to have contradicted” (Blatch v. Archer (1774), 1 Cowp. 63, 98 E.R. 969, at p. 970)]. This is, I believe, what Lord Bridge had in mind in Wilsher when he referred to a “robust and pragmatic approach to the . . . facts” (p. 569). [Emphasis added.]
[emphasis in original]
Stating the issues another way: What is the role of “common sense” in the analysis of the evidence which the judge or jury is to use to decide if factual causation has been established on the balance of probability? What does “common sense” mean in the causation analysis? What does “robust” mean?
Disclosure: I am now a member of the firm representing the defendant / applicant.
[revised to include full text of paras. 9-11 of Clements]