The Supreme Court on Monday slightly weakened the Environmental Protection Agency's power to force industrial pollution sources to curb greenhouse-gas emissions as a condition of their Clean Air Act permits.
The decision does not address EPA's recent sweeping proposal to set carbon-emissions standards for power plants, which is a centerpiece of President Obama's second-term climate agenda. Nor does it challenge EPA's underlying authority to regulate heat-trapping emissions.
Instead, the ruling addresses an existing permitting program launched several years ago.
The high court ruled 5-4 that EPA may only require newly built or modified industrial pollution sources—such as power plants, refineries, and factories—to limit greenhouse gases if those same sources must already obtain permits for their so-called conventional pollutants.
In practice, that means only a slight change in the number of big industrial polluters that would be captured by the existing, case-by-case greenhouse-gas permitting program at issue in the case decided Monday. The permitting program itself was not struck down.
The permitting program requires polluters to use so-called best available control technology, which for greenhouse gases has largely meant increased energy efficiency thus far, the Obama administration noted when defending the program before the Court in February.