Should Law and Public Policy Adopt 'Practical Causality' as the Appropriate Criteria for Deciding Product Liability Cases and Public Policy?
23 Pages Posted: 20 Aug 2012
Date Written: August 19, 2012
Abstract
The tension between the meaning of causality in science and law or public policy is well-known; however, defendants in product liability cases or industries that might be affected by a government regulation may try to convince the fact-finder to require evidence of a causal relationship that meets the standards of science. From the perspective of public health, however, people may be exposed unnecessarily to a health risk during the time period between the establishment of reasonably strong evidence of a causal relationship and the overwhelming evidence required for scientific causality. The Bayesian paradigm enables one to update information from epidemiologic studies as they accumulate, providing estimates of the probability that the relative risk of a particular harm from exposure exceeds a threshold value, e.g. 2.0 or 4.0. In order to diminish the role of the initial prior distribution, which may be quite subjective, the first case-control study or an analysis of adverse event and case reports is used to determine two prior distributions. One is the most favorable to the defendant, or industry that might be regulated, which is consistent with the previous data. The other is centered on or near the estimated relative risk from the first study. The method is applied to the studies that linked aspirin use to Reye syndrome and demonstrates that the evidence of a causal association was sufficiently strong in 1982, when the FDA first proposed that the public be warned of the risk, to support the regulation. Thus, lives would have been saved had the warning been given at the end of 1982 rather than in early 1985.
Keywords: : Bayesian inference, causality, epidemiology as evidence, preponderance of the evidence, product liability, Reye syndrome, substantial evidence
JEL Classification: C11, C40, I18, K13
Suggested Citation: Suggested Citation