Yesterday's U.S. Court of Appeals for the District of Columbia Circuit decision to uphold four greenhouse gas regulations serves as both a moral and practical victory for U.S. EPA's actions, experts say.

In an 82-page opinion, the judges affirmed EPA's right to regulate greenhouse gases with resounding authority. They found the endangerment finding and the tailpipe rule to be neither "arbitrary" nor "capricious"; that EPA's interpretation of the Clean Air Act was "unambiguously correct"; and that industry petitioners had no standing to challenge the timing and tailoring rules, because they ultimately stand to benefit, and not be harmed, from them (Greenwire, June 26).

The decision was met with joy and relief from the environmental community.

"It's such a thorough, strong affirmation of clean air standards to add climate pollution," said Vickie Patton, general counsel for the Environmental Defense Fund. "It provides an incredibly compelling foundation for agency action."

In their highly anticipated decision, the judges denied industry arguments against four Obama EPA rules. These are the endangerment finding, which established that greenhouse gases contribute to climate change and harm human health; the tailoring rule, which narrows permitting requirements to only the heaviest-emitting industries, exempting smaller facilities; the tailpipe rule, which allows EPA to create carbon standards for light-duty vehicles, in addition to the National Highway Traffic Safety Administration's fuel efficiency standards; and the timing rule, which requires that greenhouse gas emissions standards from stationary sources take effect at the same time as the motor rule.

Judges David Sentelle, David Tatel and Judith Rogers heard two days of oral arguments on the challenges in February (ClimateWire, Feb. 29).

'Momentum and support' for road ahead

The court decision comes as EPA continues to work on an ongoing suite of greenhouse gas regulations, whose development could have been stalled, or possibly terminated, had the judges ruled otherwise.

Legal challenges against the agency's first-ever greenhouse gas standards for new, diesel-burning commercial trucks and buses are being held in abeyance in a D.C. circuit court. The standards apply to model year 2014-2018 vehicles and are expected to cut carbon dioxide emissions by 270 million metric tons over the lifetime of the vehicles. Yesterday's decision undermines the basis for several of these challenges, said Patton.

EPA and NHTSA are working to develop the second phase of its fuel economy standards for light- and medium-duty vehicles, which would drive fuel efficiency for model year 2017-2025 cars to 54.5 mpg by 2025, saving approximately 6 billion metric tons of greenhouse gases throughout the duration of the program.

The agency unveiled proposed New Source Performance Standards for newly built power plants and stationary facilities in March and is working toward crafting a final rule. The agency is also expected to eventually create standards for existing sources, despite EPA Administrator Lisa Jackson's statement that there are no plans currently to address existing facilities.

In addition, EPA will eventually propose standards for greenhouse gases emanating from petroleum refineries.

Finally, EPA has granted a petition from environmental groups to assess the effects of aircraft emissions on public health.

Today's court decision will smooth the way for all of these, said Patton. "This is an incredibly powerful sign of momentum and support," she said.

The judges' decision could even apply to rules besides the landmark greenhouse gas regulations, said Jason Schwartz, legal director for the Institute for Policy Integrity at New York University. For example, a recently proposed rule on pollution from nitric acid plants could include nitrous oxide, a powerful greenhouse gas with close to 300 times the heat-trapping properties of carbon dioxide.

The judges' decision affirmed that EPA does not need to pass a quantitative threshold for how significant the danger might be, because the endangerment finding allows the agency to make more nuanced decisions, said Schwartz, accounting for factors like risk and probability in the link between greenhouse gases, climate change and health.

"What the court was affirming was EPA's authority to make these scientific judgments, to base these on science rather than questionable policy decisions," Schwartz said.

Petitioners mull options

The industry plaintiffs in the case may appeal the decision. Jeff Ostermeyer, spokesman for the National Association of Manufacturers -- one of the principal industry petitioners -- said lawyers will be deciding the next course of action over the next weeks and months.

Scott Segal, director of the Electric Reliability Coordinating Council and a partner with industry representative Bracewell and Giuliani, said EPA's authority to regulate greenhouse gases along with other pollutants doesn't necessarily affect the extent of the agency's pending or future rules.

"What today does is answer a threshold question of whether or not carbon is proper for the agency [to regulate], but it doesn't go farther than that," Segal told Greenwire (Greenwire, June 26).

In 1998, EPA's legal counsel Jonathan Cannon, issued a formal opinion stating that the agency had ample authority to address climate pollution.

The question of whether or not EPA had the right to regulate carbon peaked in 2007 with the Supreme Court decision in Massachusetts v. EPA. The justices, in a 5-4 split decision, found that greenhouse gases met the definition of a pollutant under the Clean Air Act and ordered EPA to fulfill its obligation to control emissions.

Today's decision confirms the Supreme Court's rule five years ago, applying it to its work on vehicle standards and facility emissions, said David Doniger, climate policy director at the Natural Resources Defense Council.

"You could not have had a stronger ratification or endorsement from the courts that EPA is doing its job, that the administration is doing its job properly," Doniger said.