Supreme Court to Tackle EPA Regulation of Greenhouse Gas Emissions

In its 2007 decision in Massachusetts v. Environmental Protection Agency, the U.S. Supreme Court handed federal regulators a landmark victory by holding that the "sweeping definition of 'air pollutant'" in the Clean Air Act allowed the EPA to regulate the emission of greenhouse gases. On Monday, the Supreme Court will return to this contentious area when the justices consider a new case testing the bounds of the EPA's regulatory reach.

At issue in Utility Air Regulatory Group v. Environmental Protection Agency is the EPA's 2010 determination that the Clean Air Act allows the agency to impose new permitting requirements on stationary greenhouse gas emitters, such as coal-fueled power plants. According to the EPA, although the language of the federal law may not specifically mention this regulatory expansion, a fair interpretation of the language allows for the new regulations.

The Utility Air Regulatory Group and the other legal challengers take the opposite view. As they see, the EPA has exceeded its statutory powers and effectively rewritten federal law to suit its purposes. As the challengers told the Court in one legal filing, "EPA freely acknowledged that regulation of carbon dioxide emissions under the Title I and Title V permitting programs subjects 'an extraordinarily large number of sources' to the [Clean Air Act] for the first time, contrary to explicit congressional intent to cover only a limited number of large industrial facilities."

The case therefore not only deals with the hot button issues of environmental regulation and climate change, it also raises significant questions about whether an executive branch agency violated the separation of powers.

A decision is expected by June.