Overview: Court Rules 5-4 in Massachusetts versus EPA

Supreme Court finds that EPA can regulate heat-trapping pollution, putting pressure on Congress to act on global warming

Posted: 03-Apr-2007; Updated: 07-Dec-2009

Update (12/7/2009) - Setting the stage for U.S. action on climate change, EPA formally determined today that global warming pollution imperils human health, as required by the Supreme Court's landmark ruling in 2007 (see press release and how the ruling relates to California's Clean Cars Law).

In a landmark decision, the U.S. Supreme Court has ruled that the gases that cause global warming are pollutants under the Clean Air Act. The court also found that the U.S. government has the authority to regulate carbon dioxide (CO₂) and other heat-trapping gases.

On top of other momentum — CEO endorsements, action in California and other states, hearings in Congress — this is very good news.

Although the ruling does not require the federal government to act, it puts new pressure on Congress to set a national policy that caps carbon pollution — the best way to solve this problem.

"This is ultimately up to Congress," said Environmental Defense Fund President Fred Krupp. "The Court did all it can," he said, "but if we’re really going to fix climate change, Congress must pass a cap on carbon pollution, and soon."

Two key questions of the case

The lawsuit centered on a section of the Clean Air Act that provides that the administrator of the U.S. Environmental Protection Agency "shall" set emission standards for "any air pollutant" from new motor vehicles or new motor vehicle engines "which in his judgment cause, or contribute to, air pollution which may reasonably be anticipated to endanger public health or welfare."

The case grew out of EPA’s reversal of how it interpreted its authority. In 2003, EPA reasoned that global warming pollution did not constitute an "air pollutant" within the meaning of the federal Clean Air Act. This was contrary to its opinion under the Clinton administration. (See timeline for details.)

The court's decision focused on two key substantive questions:

• Are greenhouse gases covered as pollutants under the Clean Air Act, and does EPA thus have the authority to regulate global warming pollution?
• If EPA does have that authority, does it have the right to refuse to regulate such emissions based on political or other considerations unrelated to the endangerment to human health and welfare?

On both points, the court ruled squarely in our favor. The court held that greenhouse gases are a pollutant and EPA has the authority to regulate them. The court also said that EPA can decide not to regulate "only if it determines that greenhouse gases do not contribute to climate change, or if it provides some reasonable explanation as to why it cannot or will not exercise its discretion to determine whether they do." (More on EPA's decision and our analysis.)

The court also ruled in the plaintiffs' favor on an important procedural question: namely, whether they have "standing" to challenge EPA's decision not to regulate global warming pollution from motor vehicle tailpipes. The court concluded that one petitioner, Massachusetts, does have standing. Because a case may proceed as long as at least one plaintiff is found to have standing, the court didn't rule on the standing of the other plaintiffs -- local governments and health and environmental organizations.

Now, it’s up to Congress to act

In February, the Intergovernmental Panel on Climate Change (IPCC), the leading body of experts on the issue, found that it is more than ninety percent likely that people are causing global warming. Even before this, the U.S. National Academy of Sciences (NAS) in 2005 stated that the "scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action." (Read more about the IPCC at climate411.org.)

The effects of global warming are already occurring. Extreme drought in the Southwest United States, record-breaking wildfires in the West, accelerated melting of ice sheets and fiercer hurricanes demonstrate the damaging effects of a warming world.

Yet, despite such scientific consensus and the clear and present danger of global climate change, EPA under the Bush administration has stubbornly resisted efforts to regulate greenhouse gases. Today’s ruling represents a step in the right direction, and the next step is a limit on carbon pollution.

If Congress acts soon, we can meet reduction targets by cutting our greenhouse gas emissions just 2 percent each year through mid-century. (For more on global warming and what you can do, visit FightGlobalWarming.com.)

State leadership is supported by the ruling

In the absence of national leadership, forward-looking states, cities and nongovernmental organizations have stepped up. California and 10 other states have adopted landmark programs cutting global warming pollution from motor vehicles. (More on state actions.)

A staggering amount of global warming pollution comes from U.S. cars. The U.S. has 30 percent of the world's cars, but they account for 45 percent of global automotive carbon dioxide emissions. With EPA arguing that these state clean car programs cover pollutants outside the scope of the Clean Air Act, the fate of these pollution-fighting laws was at stake.

More recently, California has passed the Global Warming Solutions Act, the first statewide effort to cap greenhouse gas emissions across all sectors of California's economy.

Coupled with California and other state action, today’s Supreme Court ruling sheds optimistic light that America can win the global warming fight. We must move quickly and urge Congress to follow through on tough climate legislation.