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

Abstract

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 work contributes to the literature converting this supposition into knowledge. This work 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. The Canadian jurisprudence is relatively sparse; while the UK jurisprudence is fulsome. By showing the fundamental dissimilarities between the intimations of 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.