Congress passed the Clean Air Act (CAA) over 50 years ago to wage a “war against air pollution.”  The CAA gives the Environmental Protection Agency (EPA) broad authority to enable it to achieve that objective.  In exercise of that authority, EPA issued a rule called the Clean Power Plan in 2015.  The Clean Power Plan set guidelines for states to follow in developing their own plans to limit carbon dioxide emissions from existing power plants.  Opponents challenged the rule, however, and the Supreme Court stayed its implementation, meaning the Clean Power Plan never went into effect.  In 2019, under the Trump Administration, EPA reexamined the Clean Power Plan, declared it unlawful, and repealed it, promulgating the Affordable Clean Energy (ACE) Rule in its place.  The American Lung Association and American Public Health Association, along with other organizations and localities, challenged EPA’s 2019 actions in several consolidated cases in the D.C. Circuit.

CAC filed an amici curiae brief on behalf of members of Congress arguing that the Clean Power Plan was lawful and, therefore, that its rescission on the ground that it was unlawful was “arbitrary [and] capricious” in violation of the CAA.  EPA contended that it repealed the Clean Power Plan because it determined that the rule exceeded EPA’s authority under the CAA.  We argued, however, that the Clean Power Plan was a lawful exercise of the broad discretion Congress gave EPA in the CAA to determine how best to reduce air pollution—discretion the Supreme Court has repeatedly recognized.  Because the Clean Power Plan was lawful, we argued that EPA’s decision to rescind it on the erroneous ground that it was unlawful was “arbitrary [and] capricious” in violation of the CAA.

In January 2021, the D.C. Circuit held that the ACE Rule and its repeal of the Clean Power Plan were arbitrary and capricious in violation of the CAA.  Mirroring our brief, the court held that “[t]he ACE Rule expressly rests on the incorrect conclusion that the plain statutory text [of the CAA] clearly foreclosed the Clean Power Plan, so that complete repeal was ‘the only permissible interpretation of the scope of the EPA’s authority.’”  Recognizing that EPA’s narrow reading of the CAA was “fundamentally . . . ‘misconceived,’” the D.C. Circuit vacated the ACE Rule and remanded to EPA, which will now develop a new plan to regulate greenhouse gas pollution from power plants.