High Court Holds EPA May Regulate Greenhouse Gases

May 16, 2007
Client Alert Newsletter May 2007

In a closely watched decision, the U.S. Supreme Court on April 2 held in Massachusetts v. EPA that the U.S. Environmental Protection Agency ("EPA") has authority to regulate carbon dioxide ("CO2") and other greenhouse gases from new motor vehicles. The case stemmed from a 1999 petition demanding that EPA regulate motor vehicle CO2 emissions under section 202(a)(1) of the Clean Air Act, which requires EPA to prescribe emission standards applicable to new motor vehicles for any "air pollutant" that may cause or contribute to air pollution "reasonably . . . anticipated to endanger public health or welfare." EPA denied the petition in 2003, asserting that section 202(a)(1) did not authorize EPA to regulate CO2 as an air pollutant as defined by the Clean Air Act. EPA also asserted that it would be unwise to do so at this time due to uncertainty surrounding global warming, and that such a regulation would be an ineffective piecemeal tool to control greenhouse gases. The environmental group plaintiffs, joined by states and other parties, appealed EPA's decision to the District of Columbia Circuit Court of Appeals. The D.C. Circuit, in a split decision, sided with EPA. The case was subsequently appealed to the Supreme Court.

In a 5-4 decision, the Court essentially ruled for the petitioners on all questions presented. First, the Court found that Massachusetts' concern of loss of coastline was a sufficiently imminent and particularized actual injury from global warming to satisfy the standing requirement. The Court then relatively easily held that EPA had authority to regulate CO2 as a Clean Air Act air pollutant under section 202(a)(1). Finally, the Court found that EPA's policy rationale for not regulating greenhouse gases at this time failed to satisfy the standards imposed by section 202(a)(1). Notably, the majority devoted several pages to the growing scientific consensus on climate change. The Court, however, refused to state that EPA was ultimately required to prescribe greenhouse gas regulations under section 202(a)(1) or that other policy considerations could not inform EPA's decision whether to regulate.