The Clean Power Plan, the Obama Administration’s attempt to reduce carbon dioxide emissions from existing power plants, had its day in court on September 27. What a day it was!

Ten judges of the D.C. Circuit Court of Appeals heard arguments addressing the validity of the EPA’s Clean Power Plan in this rare “once in a lifetime” case. (Judge Merrick Garland, an appointee to the Supreme Court, did not hear the case.) A dozen lawyers battled for nearly eight hours — far longer than the three hours the court had allotted — on issues ranging from the Plan’s constitutionality, obscure principles of statutory interpretation, congressional intent, states’ rights, and administrative procedure. Several judges questioned the manner in which EPA set the state-wide carbon dioxide goals rather than source-specific emission limits and whether EPA had the authority to regulate. Indeed, some commented that laudable ends do not necessarily legalize the means.

The court also referred frequently to the three Supreme Court cases leading up to this one that were widely cited in the parties’ briefs:  Massachusetts v EPA, in which the Court found that greenhouse gases were “pollutants” within the meaning of the Clean Air Act; AEP v. Connecticut, in which the Court held that the Clean Air Act displaced common law regulation of power plant greenhouse gas emissions; and UARG v. EPA, which found impermissible EPA’s changing of a statutory trigger to avoid “calamitous” results. The UARG Court expressed its concern with EPA’s disregard of plain statutory language as follows:

When an agency claims to discover in a long-extant statute an unheralded power to regulate “a significant portion of the American economy,” we typically greet its announcement with a measure of skepticism. We expect Congress to speak clearly if it wishes to assign to an agency decisions of vast “economic and political significance.” (internal citations omitted).

The court questioned whether the same should hold true in this case. The Clean Power Plan rule was stayed by the Supreme Court in February 2016. The D.C. Circuit’s en banc decision addressing whether the Plan is valid is expected sometime next year.