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The Supreme Court is now hearing the most closely watched environmental case in decades, which may decide the future of greenhouse gas regulation under the Clean Air Act. This case has already been the subject of an unprecedented Supreme Court stay that short-circuited the Obama administration's climate agenda and not one, but two, 7+ hour arguments before the D.C. Circuit. Jonathan Brightbill and Kevin Poloncarz, who argued the case before the D.C. Circuit, joined us to discuss what it means for the future of climate regulation and administrative law.

Under the Clean Air Act, the Environmental Protection Agency regulates greenhouse gas emissions from various sources including new cars and new industrial sources. But a large proportion of the country's greenhouse gas emissions come from existing sources, such as the nation's coal and natural gas power plants, which provide over half of American electricity.

In 2015, the Obama administration issued a regulation for existing fossil fuel power plants under Clean Air Act §111(d), which allows the EPA to “establish a procedure” for each state to adopt “standards of performance” for existing sources of air pollutants. The administration called this rule the "Clean Power Plan." It was controversial, in part, because it went beyond asking states to make their existing power plants run more efficiently. Instead, it went "beyond the fenceline" of the power plant to encourage non-fossil sources of electricity such as wind and solar power and shrink the fossil-fuel power sector.

The Clean Power Plan never went into effect because the Supreme Court stayed its implementation on February 9, 2016. The D.C. Circuit heard more than 7 hours of argument on the validity of the Clean Power Plan but never ruled on it because the Trump administration repealed it and replaced it with its own rule, which it called the "Affordable Clean Energy Rule," and was limited to promoting efficiency measures at existing fossil fuel plants. The D.C. Circuit then heard 9 more hours of argument on this new rule, before striking it down on January 19, 2021. The court held that EPA's authority was not so limited.

The Supreme Court granted certiorari to decide whether Clean Air Act §111(d) gives "the EPA authority not only to impose standards based on technology and methods that can be applied at and achieved by that existing source, but also allows the agency to develop industry-wide systems like cap-and-trade regimes." The case is an important sequel in the Court's lines of cases on how much deference executive agencies should receive to decide major questions of policy and whether Congress might authorize dramatic agency action from relatively obscure provisions—hiding an elephant in a mousehole.


  • Jonathan Brightbill, Partner, Winston & Strawn LLP
  • Kevin Poloncarz, Partner, Covington & Burling LLP
  • [Moderator] James W. Coleman, Robert G. Storey Distinguished Faculty Fellow and Professor of Law, Southern Methodist University Dedman School of Law

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As always, the Federalist Society takes no position on particular legal or public policy issues; all expressions of opinion are those of the speaker.