On January 20, 2023, faculty at the Emmett Institute on Climate Change and the Environment filed an amicus brief in the U.S. Court of Appeals for the District of Columbia Circuit supporting the right of the Environmental Protection Agency to grant a long-held waiver to California to regulate vehicle emissions more stringently than the federal government.

The brief was filed as part of the Frank G. Wells Environmental Law Clinic on behalf of Congressional Democrats by Emmett Institute Executive Director Cara Horowitz along with Emmett/Frankel Fellow Gabriel Greif and Shapiro Fellow Daniel Carpenter-Gold. The amici members of Congress are Sen. Tom Carper (D-Del), chairman of the U.S. Senate Committee on Environment and Public Works, and Rep. Frank Pallone Jr. (D-New Jersey), Ranking Member of the House Committee on Energy and Commerce. The pair has chaired the two committees with jurisdiction over the Clean Air Act. 

California has applied its own motor-vehicle emissions regulations for more than 50 years under the federal Clean Air Act, which carves out an exception for the Golden State and directs the EPA to approve those standards except under the narrowest of circumstances. That waiver has helped position California as an environmental leader in reducing air pollution and a bellwether for the auto industry. 

In May 2022, a group of Republican-led states filed a lawsuit that claims California’s waiver puts it on an uneven playing field compared to other states, in violation of the Constitution. They also contend that the authority to grant that waiver is preempted by the Energy Policy and Conservation Act of 1975. 

This brief responds that nothing in the 1975 Act preempts these air emission standards and that the legislative record shows Congress’ intent to preserve emission-reduction regulations. The brief also argues that GOP-led states are pushing a novel interpretation of the equal-sovereignty doctrine that would radically limit Congress’ legislative power. Download PDF.