Carbon Dioxide Meets Definition Of Air Pollutant

The Clean Air Act gives EPA the authority to regulate emissions of carbon dioxide and other greenhouse gases, the U.S. Supreme Court ruled on April 2.

EPA can avoid regulating CO₂ emissions from vehicles “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,” the high court ruled.

This part of the ruling compels EPA to issue such a decision, although it does not force the agency to regulate greenhouse gas emissions, says the Sierra Club, which was among several environmental groups, a dozen states, and three cities that brought the suit.

The ruling was hailed by environmental groups as an enormous victory. In its decision, the high court, by a 5–4 majority, rejected the Bush Administration’s arguments against EPA regulation of carbon dioxide emissions from new cars and trucks.

Justice John Paul Stevens, writing for the majority, said the Clean Air Act’s definition of the term “air pollutant” “embraces all airborne compounds of whatever stripe.”

“Because greenhouse gases fit well within the Act’s capacious definition of ‘air pollutant,’ EPA has statutory authority to regulate emission of such gases from new motor vehicles,” Stevens wrote. Joining him on the opinion were Justices Anthony Kennedy, David H. Souter, Ruth Bader Ginsburg, and Stephen G. Breyer.

In addition to arguing that the Clean Air Act does not give EPA authority to regulate greenhouse gases, the Bush Administration offered the court a host of reasons why EPA chose not to regulate CO₂ emissions from new vehicles. One was that voluntary federal programs to curb releases of greenhouse gases already provide a response to climate change. Another was that U.S. regulation of greenhouse gases might impair the President’s ability to negotiate with “key developing nations,” a reference likely to China and India, to reduce their emissions.

The high court said the existence other federal programs does not relieve EPA of its statutory duties to regulate pollutants under the Clean Air Act. Plus, the majority ruled, “While the President has broad authority in foreign affairs, that authority does not extend to the refusal to execute domestic laws.”

Chief Justice John G. Roberts Jr., joined by Justices Antonin Scalia, Clarence Thomas, and Samuel A. Alito Jr., dissented. They argued that Massachusetts, the lead plaintiff in the case, lacked the legal right to file the lawsuit.

Scalia filed a separate dissent arguing that greenhouse gases do not meet the Clean Air Act’s definition of air pollution. “Regulating the buildup of CO₂ and other greenhouse gases in the upper reaches of the atmosphere, which is alleged to be causing global climate change, is not akin to regulating the concentration of some substance that is polluting the air,” Scalia said.