Learning from the law to address uncertainty in the precautionary principle.

Environmentalists have advocated the Precautionary Principle (PP) to help guide public and private decisions about the environment. By contrast, industry and its spokesmen have opposed this. There is not one principle, but many that have been recommendedfor this purpose. Despite the attractiveness of a core idea in all versions of the principle--that decision-makers should take some precautionary steps to ensure that threats of serious and irreversible damage to the environment and public health do not materialize into harm--even one of the most widely endorsed principles needs considerable specification and refinement before it can be used. Moreover, the PP is an approach or guide to utilizing scientific evidence in social or legal decision-making contexts. In this it does not differ in kind from other approaches to using factual information such as in the law. The law provides some models for different strategies to guide decision-making under uncertainty when factual issues cannot be resolved with certainty. These in turn can help guide the formulation of different versions of PP and help clarify some presuppositions of the principle. Once some plausible versions of PP are articulated, I suggest some applications to existing environmental problems.