On October 15, 2013, the U.S. Supreme Court granted the appeal of various entities challenging the EPA's greenhouse gas permitting rules for stationary sources under the federal Clean Air Act (CAA). In 2007, in Massachusetts v. EPA, the court ruled that EPA may regulate greenhouse gases as air pollutants under the CAA. The decision led the EPA to regulate greenhouse gas (GHG) emissions emitted by auto mobiles, and then EPA concluded that once those gases were regulated, the EPA was required to regulate GHGs emitted from stationary sources, such as power plants and refineries. EPA then issued a series of regulations leading to permitting standards for certain very large sources that emit above a certain amound of GHGs when a new plant is constructed or an existing plant is modified.
On appeal, various state and industry groups challenged these rules on the grounds that they were based on an improper construction of the Clean Air Act and are arbitrary and capricious because they are based on an inadequate scientific record. The DC Circuit Court of Appeals rejected these appeals. The Supremen Court now has granted review of the EPA regulations, but not as to whether GHGs may be regulated at all, but on a much narrower ground.
Did the EPA permissibly determine that its regulation of greenhouse gas emissions from new motor vehicles under the Clean Air Act also triggered permit requirements for stationary sources of greenhouse gas emissions?
While narrow, the decision by the Supreme Court is an important one with respect to the EPA's program for regulating GHGs from various stationary sources. The EPA is in the process of developing standards for new power plants and existing power plants in the near future. Thus, the decision will be another landmark environmental ruling when issued.