A three-judge panel of the United States Court of Appeals for the District of Columbia declared that the agency was "unambiguously correct" that the Clean Air Act requires the federal government to impose limits once it has determined that emissions are causing harm.
The judges unanimously dismissed arguments from industry that the science of global warming was not well supported and that the agency had based its judgment on unreliable studies.
In addition to upholding the E.P.A.'s so-called endangerment finding, the court let stand related rules setting limits on greenhouse gas emissions from cars and limiting emissions from stationary sources. Opponents had also challenged the agency's timetable for enforcement and its rules singling out big polluters, but the court said the plaintiffs lacked the standing to do so.