Today the U.S. Supreme Court upheld the Environmental Protection Agency’s (EPA) authority to limit carbon pollution. Though narrowing one Clean Air Act program (the "prevention of significant deterioration" permit program), the Court confirmed that the permit program does limit carbon emissions from the biggest polluters. Of crucial importance, the Court also left undisturbed other key Clean Air Act provisions authorizing EPA to issue "performance standards" limiting carbon pollution from sources such as power plants, refineries and cement kilns. Also preserved is the EPA's authority to set limits on carbon pollution from cars and trucks, including the limits EPA has already set in 2010 and subsequent years.

Statement from Earthjustice attorney Howard Fox, co-counsel for Environmental Defense Fund in the case:

“Today marks the third Supreme Court decision confirming EPA's authority to protect us against harmful carbon pollution that threatens our health and our communities. The decision keeps the architecture in place for setting national standards to limit carbon emissions from power plants, motor vehicles, and other sources. It also provides clear momentum and authority for the EPA, as the agency moves forward with its recently announced crucial limits on carbon pollution from existing power plants.” 

In 2007, the Supreme Court ruled that carbon dioxide and other greenhouse gases are pollutants under the Clean Air Act. The EPA officially determined in 2009 that carbon pollution endangers public health and welfare, contributing (among other impacts) to heat waves that worsen smog and sea-level rise that threatens coastal communities. In 2010, the EPA issued the first-ever federal carbon pollution standards for cars and trucks, and in 2012, a federal court of appeals upheld these standards against industry challenge.

The Supreme Court's action leaves in place key portions of the 2012 decision, as well as the following:

• The EPA's 2009 finding that carbon pollution endangers public health and communities;
• Emission standards the EPA issued in 2010 (and subsequent years) limiting carbon pollution from cars and trucks;
• The EPA's authority under the Clean Air Act to adopt emission standards ("performance standards") for power plants and other stationary sources of carbon pollution; and
• Key portions of the EPA's regulations (under the "prevention of significant deterioration" permit program) requiring major new and modified pollution sources such as power plants and factories to use the best available technology to limit carbon emissions.

The Clean Air Act's "prevention of significant deterioration" permit program requires that new and modified major stationary polluters such as power plants and factories use the best available technology to control their air pollution. Industry and its allies filed lawsuits seeking to exempt carbon pollution from this safeguard. While today's Supreme Court ruling does excuse some pollution sources from this requirement, the requirement will remain in effect for the worst carbon polluters, which account for roughly 83 percent of U.S. stationary source greenhouse gas emissions.

Related Documents

• Read today's Supreme Court decision
• Read environmental groups' Supreme Court brief

History Of Supreme Court's Rulings Confirming EPA's Authority To Tackle Carbon Pollution

In a 2007 case about motor vehicle emissions, the Supreme Court ruled that carbon pollution and other greenhouse gases are air pollutants under the Clean Air Act, and that the EPA must limit carbon pollution if such pollution contributes to climate change. Massachusetts v. EPA, 549 U.S. 497 (2007).

In 2011, the Supreme Court confirmed EPA's authority under the Clean Air Act to issue "performance standards" limiting carbon pollution from stationary sources such as electric power plants. American Elec. Power Co. v. Connecticut, 131 S. Ct. 2527 (2011).

In the case decided today, the Supreme Court vindicated the EPA's endangerment finding and the agency's ground-breaking limits on carbon pollution from cars and trucks when the Court declined to take up challenges to those critically important actions. The Court also left undisturbed EPA's authority to set "performance standards" for power plants and other carbon emitters, and in addition confirmed that a separate Clean Air Act safeguard (the "prevention of significant deterioration" permit program) requires use of the best available technology to limit carbon pollution from the worst polluters.