The European Union enshrined the "precautionary principle" with respect to environmental issues in its treaty law in 1992. Legal confusion surrounding use of that principle has since ensued and continues despite a useful attempt by the European Commission to clarify and limit (but not define) the principle in 2000. It has been extended to public health and safety and invoked on dozens of occasions, often in court. As the authors of this short book demonstrate, the European courts have simply added to the confusion. Some decisions regard the precautionary principle as too vague to have operational meaning. Others have interpreted it as barring virtually any action that might pose a risk to the environment or to public health, even when scientific panels have found no discernible risk and despite the commission's 2000 clarification that the principle does not imply zero risk. Hence the authors' claim that it introduces an "arbitrary and capricious" element into European policymaking.