Challenges To EPA's Repeal Of The 2009 Endangerment Finding

Introduction

On February 12, 2026, the U.S. Environmental Protection Agency ("EPA") finalized a rule repealing the 2009 Endangerment Finding—the agency's formal determination that greenhouse gas ("GHG") emissions from motor vehicles contribute to air pollution that endangers public health and welfare—and repealing all federal GHG emission standards for motor vehicles and engines. Two waves of litigation have followed shortly after the publication of the final rule, and continue to develop as briefing is scheduled.

Background: The Endangerment Finding and Its Rescission

The 2009 Endangerment Finding was the direct result of the landmark 2007 Supreme Court decision in Massachusetts v. EPA, in which the Court held that greenhouse gases are "air pollutants" under the Clean Air Act and directed EPA to determine, based on the science, whether such emissions endanger public health or welfare. Following years of scientific review, EPA concluded in 2009 that six key GHGs—including carbon