Although the Clean Air Act has no provisions to directly regulate greenhouse gas emissions, the Supreme Court enabled such regulation in 2007, opening the door for a vast expansion of the EPA’s regulatory powers.
- The Clean Air Act (CAA) does not explicitly call for the regulation of greenhouse gases (GHGs), and the clear intent of Congress was to avoid such regulation. However, legal maneuvering has made GHG regulation possible under the CAA.
- In 2007, the Supreme Court determined in Massachusetts v. EPA that GHGs are air pollutants and that the EPA must decide whether they endanger human health to the degree required by the CAA for regulation.
- In 2009, under President Obama, the EPA issued a finding of endangerment for GHG emissions from vehicles, beginning a broad campaign to enact GHG regulations under the CAA.
- Under President Trump, the EPA limited GHG regulation but declined to eliminate any endangerment findings for GHGs.