Uncertain risk, causation and precaution in toxic tort litigation


University of British Columbia

Date Issued


Document Type



Master of Laws - LLM




The requirements for proof of causation determine the extent to which the general public will be exposed to risks associated with technological and scientific processes. If the requirements for proving causation are set too high, individuals will be less successful in protecting their rights to personal integrity and property. As such, the general public will be exposed to greater risk of harm by toxic substances associated with industrial activities. Conversely, technological and scientific advancement will be stifled by overly lax causation requirements which place an excessive burden on the producers and users of toxic substances. Due to the limits of scientific knowledge, the traditional requirements for proof of causation present an almost insurmountable barrier to success in toxic tort litigation. In particular, the risk associated with a particular industrial process may be unknowable in light of current scientific knowledge. The traditional causation requirements are unsuited to the situation in which scientific evidence can demonstrate a significantly increased risk of harm but cannot establish a conclusive causal link. The courts should expressly acknowledge the scientific uncertainty surrounding the risk associated with many industrial activities, and explicitly adopt a policy approach to dealing with this uncertainty. At one extreme, the courts may allow these processes to proceed until there has been clear demonstration of harm. At the other extreme, the courts may disallow these processes to proceed until there has been clear demonstration of safety. Falling between these extremes, the courts may allow cautious progress with these processes until there has been clear demonstration of harm or safety. The latter approach allows a balance between the social benefit of technological and scientific advancement and the individual rights to personal integrity and property. In the context of toxic tort litigation, this approach can be adopted by moving from a formulaic conception of causation to a flexible, policy sensitive conception which is guided by the notion of precaution. Ultimately, the courts' selection of an approach to dealing with scientific uncertainty is a matter of policy which should be resolved by consideration of the values in conflict in toxic tort litigation.

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Law, Peter A. Allard School of