Last year, I discussed the ruling of the U.S. Court of Appeals for the District of Columbia Circuit upholding the EPA's first round of regulations on greenhouse gases. To quickly summarize, the EPA had issued four sets of regulations: an endangerment finding (concluding that greenhouse gases did contribute to climate change and therefore met the definition of a pollutant for purposes of mobile sources); a "tailpipe" rule (establishing regulations to reduce greenhouse gas emissions from motor vehicles and other mobile sources); and "timing" and "transition" rules governing emissions from stationary sources (e.g. power plants).
Not too surprisingly, the plaintiffs in those cases -- several "red" states and business groups separately filed requests for the Supreme Court to review different aspects of the D.C. Circuit's ruling. Last Tuesday, the Supreme Court decided which parts of the case it would take. The Supreme Court denied three of the nine applications in their entirety. For the remaining six, the Supreme Court only took one issue -- whether the EPA's traditional position that, if a substance qualifies as a pollutant for mobile sources, the EPA is also authorized to regulate emissions of that substance from stationary sources.
By limiting the case to this one issue, the Supreme Court let stand the finding of the EPA that greenhouse gases are a pollutant and the finding that the Clean Air Act requires the EPA to regulate motor vehicles to reduce the level of greenhouse gases. In doing so, it has dramatically undermined the false claim that the EPA's regulation of greenhouse gases is outside the scope of the EPA's authority.
More significantly, the one issue on which the Supreme Court did grant review is not a new issue and is not limited to greenhouse gases. Instead, it is a position that the EPA has consistently applied for the forty years of its existence. The consistent interpretation of the Clean Air Act by the EPA is an argument in favor of the majority upholding the current set of regulations. A contrary interpretation would dramatically change how the Clean Air Act is applied across the board and would call into question multiple regulations, but only on technical grounds. The EPA's current bottom line is that the definition of a pollutant is the same for all parts of the Clean Air Act so a finding that a substance is a pollutant for one part of the Clean Air Act is sufficient to allow regulation under all parts of the Clean Air Act. If the Supreme Court finds that this is not the case, presumably the Supreme Court would explain how the requirements for the different parts of the Clean Air Act differ. As such, ultimately, most if not all, of the regulations governing various pollutants from stationary sources would be re-adopted after those additional findings where made including the regulations on greenhouse gases.
Bottom line is that last Tuesday's ruling was a big setback to climate change deniers; now if only that message would sink in on Capitol Hill.