Upholding EPA Regulation of Greenhouse Gases: The Precautionary Principle Redux

Abstract

The debate over the precautionary principle versus cost-benefit analysis in environmental decision making has engaged legal and policy experts for decades. At its heart, the precautionary principle counsels that governmental action should be taken to reduce the risk of serious harms, even if the evidence defining the harm is not sufficient to meet the evidentiary standard of certainty in a civil proceeding, and even if uncertainty is too great to be able to quantify and compare costs and benefits with precision. In Coalition for Responsible Regulation v. EPA, the U.S. Court of Appeals for the District of Columbia Circuit upheld EPA’s regulation of greenhouse gas emissions from motor vehicles on the ground that such emissions endanger public health and welfare. Both EPA and the court placed primary reliance on the precautionary principle of the Clean Air Act’s endangerment standard as construed in the 1976 D.C. Circuit case Ethyl Corp. v. EPA, upholding EPA’s regulation of another motor vehicle pollutant, lead emissions resulting from the use of lead additives in gasoline. This Article contends that the issues and outcomes of the two regulatory decisions demonstrate why a precautionary approach — balancing probability and severity of harm and acting before full quantification of benefits and costs is possible — is a necessary framework for sound decision making on the most complex and consequential threats to the environment, including the extraordinary challenge of climate change.Reliance on quantified cost-benefit analysis has become the prevailing approach in U.S. environmental decision. The Article rejects the view that cost-benefit analysis alone should determine environmental regulatory decisions as well as the opinion that precaution excludes consideration of such analysis. To explore these issues, the Article analyzes and compares the lead additive and greenhouse gas decisions with reference to the uncertainty of the relevant science and the level of quantification of regulatory benefits and costs. The Article also considers whether scientific advances since each decision was made confirm or call into question EPA’s regulatory actions and contends that a precautionary approach will be necessary and appropriate to assess the justification for regulating existing electric power plants under the Clean Air Act. The conclusion identifies several elements of reasoned decision making under a precautionary standard as well as the major public benefits gained and likely to be gained by the two EPA decisions reducing automotive lead and greenhouse gas emissions.