Supreme Court Upholds EPA Rule on Interstate Air Pollution

The 6-2 decision in EPA v. EME Homer City Generation upholds the Transport Rule, which requires emission reductions by power plants in upwind states that "contribute significantly" to downwind states' nonattainment of EPA's air quality standards.

The U.S. Supreme Court ruled April 29 in favor of EPA in an important case, EPA v. Homer City Generation, L.P., No. 12-1182, which challenged the agency's Transport Rule, issued in August 2011 in furtherance of the Clean Air Act. The rule sets emission reduction obligations for power plants in 27 upwind states that "contribute significantly" to downwind states' nonattainment of EPA air quality standards.

Power companies; coal companies; states including Texas, Michigan, and Ohio; and some other parties challenged the rule's legitimacy in court and won a victory in August 2012 when the U.S. Court of Appeals for the D.C. Circuit held that the rule exceeded EPA's authority .

But the Supreme Court reversed the appeal court in a 6-2 decision written by Justice Ruth Bader Ginsburg. The decision means about 1,000 power plants, mainly in the eastern half of the United States, must adopt new pollution controls to limit emissions of nitrogen oxide and sulfur dioxide.

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