Legal Consequences of EPA's Endangerment Finding for New Motor Vehicle Greenhouse Gas Emissions

On December 15, 2009, the Environmental Protection Agency (EPA) took its most important action to date related to climate change. EPA published its final determination that the combined greenhouse gas (GHG) emissions from new, light-duty motor vehicles in the United States contribute to an “endangerment” from climate change. More precisely, EPA found that such emissions, in the words of Clean Air Act (CAA) section 202(a), “cause or contribute to air pollution that may reasonably be anticipated to endanger public health or welfare.” Under section 202(a), this finding requires that EPA promulgate “standards” to control such emissions—as the agency proposed to do in advance of its endangerment determination.


Some groups have objected to the endangerment determination and the emission standards to follow, arguing they will trigger a “cascade” of unacceptable regulatory consequences under other CAA provisions. These regulatory consequences, they say, would impose unattainable GHG-concentration goals on EPA and the states, and/or economically and administratively unreasonable burdens. This report examines the CAA provisions that have figured in this debate to see whether this alleged cascade of legal consequences likely would occur.


First, the report examines CAA sections that, like section 202(a), are triggered by endangerment findings. Of these, the one most likely to require EPA regulatory action after the 202(a) endangerment finding is section 111, authorizing new source performance standards—but only as to stationary source categories emitting the largest amounts of GHGs. Section 111, however, affords EPA wide discretion in setting new source performance standards. Two other sections that arguably might be triggered are 108, requiring national ambient air quality standards, and 115, which requires states to revise their implementation plans to prevent or eliminate the endangerment of public health or welfare in a foreign country. As to these sections, however, the arguable infeasibility of the regulatory goals—even if GHG emissions in the United States are significantly reduced, atmospheric concentrations would decline little—will give EPA room to argue that regulatory action is not mandatory. Other endangerment-triggered sections of the CAA can be distinguished from section 202(a) by their explicit terms, and thus would likely not be triggered by the 202(a) endangerment finding.


Second, the report looks at CAA provisions having no endangerment trigger. Of these, EPA has conceded that two require the agency to act after it promulgates the required emission standards following the 202(a) endangerment finding. One provision would require EPA to impose “best available control technology” (BACT) on GHG emissions from any major emitting facility proposed to be constructed in a Prevention of Significant Deterioration area. The other, Title V, creates an operating permit program for stationary sources of emissions, and would require stationary sources subject to BACT under the first provision to also apply for Title V permits. As to each of these requirements, EPA has proposed a “tailoring rule” setting emission thresholds far higher than in the CAA, at least for a few years. EPA justifies the departure from statutory language under the case law doctrines of “absurd results” and “administrative necessity.”


A caveat: the issue analyzed in this report is important primarily if Congress does not enact climate change legislation that puts regulation of GHGs beyond the reach of some of the CAA provisions discussed here. In particular, the House-passed climate change bill, H.R. 2454 (the American Clean Energy and Security Act of 2009), states that three of the CAA sections treated in this report, and one CAA title, may not be used to address air pollutants based on their climate change impacts.

Date of Report: December 15, 2009
Number of Pages: 20
Order Number: R40984
Price: $29.95
Document available electronically as a pdf file or in paper form.
To order, e-mail congress@pennyhill.com or call us at 301-253-0881