The precautionary principle, also referred to as the precautionary approach, justifies the use of cost-effective measures to prevent environmental degradation even in the absence of full scientific certainty. This principle has obvious applications to various forms of environmental pollution. The principle can be traced to German national law in 1976, which states, "[e]nvironmental policy is not fully accomplished by warding off imminent hazards and the elimination of damage which has occurred. Precautionary environmental policy requires furthermore that natural resources are protected and demands on them are made with care."

The principle's first applications beyond national boundaries came in 1987. It was quickly adopted into numerous multilateral treaties and international declarations, including the 1987 Montréal Protocol on Substances that Deplete the Ozone Layer, the 1990 Bergen Declaration on Sustainable Development, the 1992 Convention on Biological Diversity, and the 1999 Treaty of Amsterdam, which has broadened and redefined the goals and institutions of the European Union.

The principle's scope varies dramatically in these documents as well as in national legislation that contains it. In some, it is limited to toxic substances that are persistent and can bioaccumulate. In others, like the Bergen Declaration, it covers all government policies with the potential to degrade the environment, even when some causal relationships have not been fully established scientifically. Some critics contend that the Principle restricts technology. It has been a focus of U.S.–European Union (EU) trade disputes, as Europeans have argued for its application to genetically modified foods, animal-growth-promoting hormones, and phthalates (softeners) in polyvinyl chloride (PVC) children's toys. The U.S. government also contends that the principle is a nontariff barrier, that is a policy that interferes with exports or imports other than a simple tariff such as quota.

Bibliography

Goklany, Indur M. (2001). Precautionary Principle: A Critical Appraisal of Environmental Risk Analysis. Washington, D.C.: Cato Institute.