On April 8, judges in the U.S. Court of Appeals for the District of Columbia Circuit questioned whether the Environmental Protection Agency (EPA) had the authority under the Clean Air Act to exempt certain facilities that burn biomass from operating permits for greenhouse gas emissions. The 2011 rule, which would exempt new and modified biomass facilities through July 2014, is the subject of a suit filed by the Center for Biological Diversity, the Clean Air Task Force, and the Natural Resources Defense Council. The EPA responded that the exemption was set up through 2014 to allow time to study biomass emissions and possible regulation options.