Unpacking the EPA's Endangerment Finding: A Key Pillar in U.S. Environmental Policy Now Under Review The EPA's 2009 Endangerment Finding determined that greenhouse gases like CO2 endanger public health and welfare, based on scientific evidence and a 2007 Supreme Court ruling in Massachusetts v. EPA. This enabled regulations on emissions from vehicles and power plants to address climate impacts. On February 12, 2026, the EPA repealed it, citing legal reinterpretations from recent court decisions