On October 29, 2021, the U.S. Supreme Court granted certiorari in West Virginia v. Environmental Protection Agency, a petition filed by several states and coal companies attacking the U.S. Environmental Protection Agency's (EPA’s) regulatory authority under the Clean Air Act (CAA). The Court’s holding in this case would determine EPA’s continued ability to use the CAA—including the national ambient air quality standard (NAAQS) program—as a climate change tool.

On the final day of the 2021-2022 term, the U.S. Supreme Court released its decision in West Virginia v. Environmental Protection Agency. The majority (6-3) opinion limited the U.S. Environmental Protection Agency’s (EPA’s) authority to regulate greenhouse gas emissions from power plants under Clean Air Act §111(d), in part by invoking the “major questions doctrine.” The decision has implications for EPA’s authority both to regulate emissions from stationary sources and to regulate greenhouse gases more broadly.