Scientific Evidence and the Law: An Objective Bayesian Formalization of the Precautionary Principle in Pharmaceutical Regulation

Abstract

The paper considers the legal tools that have been developed in German pharmaceutical regulation as a result of the precautionary attitude inaugurated by the Contergan decision (1970). These tools are (i) the notion of ―well-founded suspicion‖, which attenuates the requirements for safety intervention by relaxing the requirement of a proved causal connection between danger and source, and the introduction of (ii) the reversal of proof burden in liability norms. The paper focuses on the first and proposes seeing the precautionary principle as an instance of the requirement that one should maximise expected utility. In order to maximise expected utility certain probabilities are required and it is argued that objective Bayesianism offers the most plausible means to determine the optimal decision in cases where evidence supports diverging choices. 1. Precautionary attitudes in response to uncertain knowledge Historically, the precautionary principle arose in response to the lessons learnt from environmental disasters and injuries to human and animal health caused by chemical compounds (x-ray radioactivity, benzene, asbestos, PCB, halocarbons, DES sulphur dioxide, etc.). These tragedies could have been avoided if signals of alarm had been taken more seriously. This hindsight, together with the increasing awareness of the unpredictability of environmental and health effects created by the chemical industry, stimulated the development of juridical instruments for the management of lack of knowledge—see, for instance, the work done by the European Environmental Agency (2001). These instruments are meant to be able to enlarge the powers of intervention for authorities against sources of possible harm, even in the absence of scientific proof of a causal link. Causal link is the central notion in this context because it is the basis both for action on the one hand, and for responsibility attribution on the other hand. The first programmatic documents advocating administrative intervention before a causal connection be scientifically established were developed in relation to