The Environmental Protection Agency ruled  that new power plants are not required to install technology to reduce carbon dioxide emissions, rejecting an argument from environmental groups. The ruling turns on a seemingly arcane regulatory question that could govern the future of new fossil fuel-burning buildings and power plants under the Clean Air Act.

During the Bush administration, the EPA has rejected the idea that greenhouse gases should be regulated like soot, smog precursors and other kinds of air pollution, despite an April 2007 Supreme Court ruling that said carbon dioxide fit the definition of a pollutant that could be regulated under the Clean Air Act.