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Colorado joins lawsuit over EPA climate rollback
ColoradoBiz Staff //March 19, 2026//
DENVER — Colorado has joined a coalition of states, cities and counties challenging a U.S. Environmental Protection Agency effort to rescind its 2009 endangerment finding on greenhouse gas emissions.
In Brief:
- Colorado joins coalition challenging EPA climate policy rollback
- Lawsuit targets rescinding 2009 greenhouse gas endangerment finding
- Action seeks to preserve vehicle emissions standards
- Coalition includes states, cities and the City and County of Denver
The finding determined that greenhouse gas emissions from motor vehicles contribute to climate change and endanger public health and welfare. It followed the 2007 U.S. Supreme Court decision in “Massachusetts v. EPA,” which affirmed the agency’s authority to regulate such emissions under the Clean Air Act.
State officials said the lawsuit seeks to block the EPA from eliminating vehicle greenhouse gas standards tied to that finding.
“We in Colorado know all too well the effects of climate change,” Attorney General Phil Weiser said, citing drought, wildfires and low snowpack. “The EPA has no legal or scientific basis to roll back the endangerment finding.”
The EPA action would rescind the finding and repeal greenhouse gas standards for motor vehicles. The coalition argues the move conflicts with established law and scientific evidence.
Colorado is part of a group led by attorneys general from California, Connecticut, New York and Massachusetts. The coalition also includes multiple states, local governments and the City and County of Denver.
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