Full Title: Exhaustive Precedent
Author(s): Dena Adler and Kate Welty
Publisher(s): Policy Integrity
Publication Date: July 23, 2025
Full Text: Download Resource
Description (excerpt):
Section 202(a)(1) of the Clean Air Act requires the Environmental Protection Agency (EPA) to regulate emissions from new motor vehicles that “cause, or contribute to,” dangerous air pollution. In 2007, the Supreme Court issued a landmark ruling that greenhouse gas emissions are covered by Section 202(a)(1) and that EPA must regulate those emissions from new motor vehicles if the agency finds that they contribute to air pollution that endangers public health or welfare. In 2009, EPA made the requisite findings concerning endangerment and contribution based on extensive, peer-reviewed science and thousands of public comments. As a result, EPA established standards for greenhouse gas emissions for light-duty vehicles in 2010, and for medium- and heavy-duty vehicles in 2011. In the ensuing years, EPA has strengthened its emission standards for motor vehicles several times.