Causal Draws and Causal Inferences: A Solution to Clements v. Clements (and Other Causation Cases)

39 Advocates Quarterly 241 (2011)

16 Pages Posted: 4 Jun 2012

See all articles by Erik S. Knutsen

Erik S. Knutsen

Queen's University Faculty of Law

Date Written: December 19, 2011


Nothing in tort causes more confusion than causation. In early 2012, the Supreme Court of Canada will hear Clements (Litigation Guardian of) v. Clements,1 on appeal from the British Columbia Court of Appeal. At trial and appeal, this case pitted negligence law’s default “but for” test for causation against the alternative material contribution test for causation. When does a court use one test or the other? How can litigants sensibly predict case results? Clements is a case about a motorcycle accident where the passenger was severely injured because the motorcycle capsized as a result of a punctured tire. The driver was speeding in wet weather and had improperly overloaded the motorcycle. The evidence was unable to definitively explain the specific causal role that the driver’s negligence played in the motorcycle upset and resulting injuries to the passenger (who was the driver’s wife).

This case is an illustration that causation is getting too confusing. Confusion breeds consistency costs. A return to first principles and simple foundational doctrine would go a long way to rehabilitating the thinking about causation and how to prove it. As will be discussed below, this case should probably not be about dueling doctrinal tests for causation at all but instead about how courts determine evidentiary sufficiency for causal proof.

Keywords: causation, tort, cause, material contribution, causal proof

Suggested Citation

Knutsen, Erik S., Causal Draws and Causal Inferences: A Solution to Clements v. Clements (and Other Causation Cases) (December 19, 2011). 39 Advocates Quarterly 241 (2011), Available at SSRN:

Erik S. Knutsen (Contact Author)

Queen's University Faculty of Law ( email )

Macdonald Hall
128 Union Street
Kingston, Ontario K7L 3N6
613-533-6000 ext. 78360 (Phone)
613-533-6509 (Fax)


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