US Supreme Court reaches key decision on greenhouse gases

In one of its most important environmental decisions in years, Massachusetts v. Environmental Protection Agency, the United States Supreme Court announced on April 2, 2007 that it would direct the agency (EPA) to reconsider its refusal to regulate heat-trapping gases in automobile emissions. Led by the State of Massachusetts, a dozen states and several US cities and environmental groups went to court to try to force the EPA to regulate greenhouse gases such as carbon dioxide emissions. The petitioners claimed that human-influenced global climate change was causing adverse effects – among them, a vanishing Massachusetts coastline.

The EPA gave several reasons for declining to regulate greenhouse gas emissions under the Clean Air Act, including its concern that climate change is a foreign policy issue to be addressed by the president.

The EPA argued that it was not given the authority under the Clean Air Act to regulate CO2 or other greenhouse gases. The Supreme Court challenged the EPA’s refusal to regulate CO2 as an air pollutant under the statute, and then ruled that CO2 fits within the statute’s broad definition of an air pollutant. Further, the Court stated that “[the] EPA identifies nothing suggesting that Congress meant to curtail EPA’s power to treat greenhouse gases as air pollutants.”

The EPA argued in its defence that regulating CO2 would require regulating fuel economy standards, which – according to the EPA – is under the purview of the Department of Transportation. The Court countered by acknowledging that multi-agency efforts can indeed overlap when addressing an issue as important as global climate change: “The fact that the Department of Transportation’s mandate to promote energy efficiency by setting mileage standards may overlap with EPA’s environmental responsibilities in no way licenses the EPA to shirk its duty to protect the public health and welfare.”

Finally, the EPA argued that even if it was granted authority to regulate greenhouse gases under the Clean Air Act, it would be “unwise to do so at this time,” adding that it might conflict with the current administration’s effort to address climate change, particularly with regard to international climate negotiations.

The Court deemed insufficient the EPA’s argument that regulating emissions from the transportation sector “might hamper the President’s ability to persuade key developing nations to reduce emissions.” Rather, according to the Court: “A reduction in domestic emissions would slow the pace of global emissions increases, no matter what happens elsewhere.”

Further, the Court said the Clean Air Act makes it clear that “the EPA can avoid promulgating regulations only if it determines that greenhouse gases do not contribute to climate change, or if it provides some reasonable explanation as to why it cannot or will not exercise its discretion to determine whether they do.”

Finally, the Court was unconvinced by the EPA’s argument that CO2 regulation in the transportation sector would not make significant reductions in emissions, stressing nonetheless the EPA’s duty to take such a steps in order to “slow or reduce” global warming.

The Court’s decision opens the door for greenhouse gas regulation under the Clean Air Act, it is also likely to catalyse calls for more comprehensive federal climate change legislation – legislation that covers sectors other than transportation, as well as non-CO2 greenhouse gases.