Most famously, in Massachusetts v. EPA, the Court ruled that the Environmental Protection Agency (“EPA”) had the authority under the Clean Air Act (“CAA”) to regulate greenhouse gas emissions, clearing the way for EPA’s recent (and future) efforts to reduce these emissions and combat climate change. While the Court turned away industry challenges to the core of Massachusetts v. EPA when it granted review in UARG, it did agree to hear a narrow challenge to EPA’s decision to apply the CAA’s Prevention of Significant Deterioration (“PSD”) program to stationary sources of greenhouse gas emissions.

The CAA’s PSD permitting program was designed to prevent the significant deterioration of air quality in areas that were already complying with the national ambient air quality standards for at least one criteria pollutant. Taking up its charge following the Court’s ruling in Massachusetts v. EPA, the EPA introduced new regulations covering greenhouse gas emissions from motor vehicles. EPA then extended the PSD permitting program to cover large stationary sources of greenhouse gas, as required by the plain text of the CAA and a three-decades-old interpretation of the Act followed by both Democratic and Republican Presidents alike. Although industry groups challenged this decision, the U.S. Court of Appeals for the D.C. Circuit upheld EPA’s actions in full, describing them as “unambiguously correct” and “statutorily compelled.” The industry groups successfully petitioned the Supreme Court to hear the case (although the Court confined the groups’ challenge as noted above).

On January 28, 2014, CAC filed an amicus curiae brief in support of the government in UARG, urging the Court to affirm the D.C. Circuit’s decision and to uphold the EPA’s regulation of greenhouse gas emissions under the PSD permitting program. Air pollution, including the massive challenge posed by greenhouse gas emissions, presents a complex and truly national problem, and, as we demonstrated in our brief, is thus precisely the sort of problem that the Framers envisioned our national government addressing. Correcting the recognized deficiencies of the Articles of Confederation, the Framers carefully designed a federal government with the power to address truly national problems, with Congress enacting related laws and the President “faithfully” carrying out those laws with “energy.” The CAA is a quintessential example of what the Founders had in mind – a statute dealing with a problem that implicates “the general Interests of the Union” and “which the States are separately incompetent” to address. In enacting the CAA, Congress identified a massive, ever-changing national problem and provided the executive branch with the tools necessary to address it.

Our brief demonstrated that EPA’s extension of the PSD permitting program was consistent with its longstanding interpretation of the CAA as well as the plain text of the statute. The CAA is a broadly worded law that was purposefully crafted to deal with a complex, ever-changing problem like air pollution without requiring congressional action every time information arises about a particular new pollutant. Congress chose to define air pollutants in “sweeping” and “capacious” terms. Far from “rewriting” the statute by phasing in regulations, as the industry groups and their amici claimed, EPA was carrying out the CAA’s requirements one step at a time, addressing the vast majority of greenhouse gas emissions by stationary sources at the outset and charting a path for expanding the program to cover additional sources later.

The Court heard oral argument in UARG on February 24, 2014. On June 23, 2014, the Court issued its decision, agreeing with one of the government’s main arguments and rejecting another. By a 7-2 vote, the Court held, in an opinion authored by Justice Scalia and joined by Chief Justice Roberts, Justice Kennedy, and the Court’s progressive Justices, that EPA may regulate greenhouse gas emissions of any “major emitting facility” already required to receive a permit under the CAA’s PSD program due to its emission of other air pollutants, which covers roughly 83 percent of stationary sources of greenhouse gas emissions in America. The Court determined that the EPA “reasonably interpreted the Act” under this reading of the statute.

In the second part of its decision, the Court was divided ideologically, 5-4, with the Court’s conservative majority holding that the Clean Air Act did not allow EPA to extend the PSD program permitting requirements based solely on a source’s greenhouse gas emissions, which would have covered approximately 86 percent of the stationary sources of greenhouse gas emissions. Justices Breyer, Ginsburg, Sotomayor, and Kagan dissented from this part of the Court’s ruling.