Hows, whys and but-fors : theorizing, comparing and solution finding within the principle of material contribution to risk in the law of negligence


University of British Columbia

Date Issued


Document Type



Master of Laws - LLM




This thesis will provide a significant and original contribution to the scholarship on tort causation. Material contribution to risk is a principle of tort causation; yet has never been applied. It may potentially violate all of the principles that underpin tort causation, whatever those principles may be. Alternately, it may simply be another conventional adaptation of tort causation to avoid manifest injustice. The supposition is that it will fall somewhere between. This thesis contributes to the literature converting this supposition into knowledge. This thesis has three parts. The first seeks to do what few in tort writing do: craft a methodology. The first part compares and contrasts the theory that underpins tort law, the law of negligence, and finally, the theory of causation. Any choice in the latter part of the article is obviously conditioned on which theory explains the actual benefits and harms of such a choice. The second part uses comparison to determine where the Canadian law of material contribution to risk currently rests. By showing the fundamental dissimilarities between the Canadian and UK jurisprudence, this part shows that the two jurisdictions are, and should continue to be, unique. The third part considers two areas of material contribution to risk that are fundamentally unclear. Firstly, circumstances in which material contribution to risk can apply in lieu of the de facto but-for test are, at best, transparent. This section is termed the ‘trigger’ section—and probes when material contribution to risk can be applied instead of the de facto but-for test. Secondly, who is liable for what under material contribution to risk is also unclear. This section is termed apportionment—and determines which liability rule should determine which defendant should be liable for what share of the damages. This thesis makes an original contribution to the literature by defining the underlying theory of causation in negligence through the application of robust methodology; defining the Canadian law of material contribution to risk; and finally, establishing both what the trigger is, and what apportionment should be, in relation to material contribution to risk.

Date Available



Attribution-NonCommercial-NoDerivs 2.5 Canada




Law, Peter A. Allard School of