It’s a simple but powerful question: Does the U.S. EPA have the power — and the obligation — to regulate carbon dioxide as an air pollutant under the Clean Air Act? Strangely, it still remains partially unanswered, even though it was a central issue in a landmark court case decided on Friday.

Spew away, appeals court says.

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In a major legal victory for the Bush administration, a three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit ruled against 12 states, three cities, and more than a dozen environmental groups that had argued the EPA was obligated by the Clean Air Act to regulate CO2 emissions from cars and trucks, given the public health threat that climate change poses.

“Sadly, this confirms what the administration has made abundantly clear for five years: They are not going to do anything on climate change, except either deny that it’s happening or say there’s nothing they can do about it,” said Sierra Club attorney David Bookbinder, who helped litigate the case. “Now it’s up to Congress and the states to do something about this.”

The Bush EPA, for its part, was happy that the 2-1 decision validated its approach (or lack thereof) to climate regulation. “We are so pleased that the court supported our decision to use voluntary measures such as Energy Star and methane markets, as opposed to litigation and mandatory regulation that does not promote economic growth,” EPA Press Secretary Eryn Witcher told Muckraker.

Industry representatives are going a step further and calling the decision a substantiation of their view that the science on global warming is still uncertain. “The court found that the science is not only inconclusive, but there’s a significant amount of disagreement about the potential health effects of climate change — there’s a lot of speculation,” said Lisa Jaeger, former acting general counsel for the EPA and a partner at Bracewell & Giuliani LLP, which represents energy interests. She quoted the section of the majority opinion written by Judge A. Raymond Randolph in which he claims that the “understanding of the relationships between weather/climate and human health is in its infancy.” Attorneys general from 11 states who went to bat for the administration during the suit — including Michigan and Texas — also applauded the outcome.

Enviros, on the other hand, bristled at the decision. “Only one of the three judges addressed the central question in the case, ruling that the Clean Air Act empowers EPA to curb the pollution that causes global warming,” said David Doniger, senior attorney with Natural Resources Defense Council and policy director of its Climate Center, who also helped argue the case. Doniger explained that while the Clean Air Act directs the EPA to regulate air pollutants from motor vehicles “which may reasonably be anticipated to endanger public health or welfare,” the two judges who ruled against the plaintiffs were looking for the kind of proof that’s necessary in a criminal case. “Judge Randolph says, effectively, you have to have proof beyond a reasonable doubt. But in fact the Clean Air Act sets a much lower hurdle, regulating pollutants that can reasonably be anticipated as a danger.”

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John Stanton, vice president of National Environmental Trust, stresses that the decisions of Randolph and his cohort David Sentelle must be seen in the context of their political backgrounds. “Randolph was appointed by George Bush Sr. and Sentelle was appointed by Reagan. Both have consistently voted down-the-line conservative, and both have anti-environmental track records. It was clear that they were not going to rock the boat on a highly politicized issue.”

A close look at the written opinions [PDF] of Randolph and Sentelle reveals that several of their reasons for rejecting the plaintiffs’ case are irrelevant to issues of public health or environmental policy, and could be perceived as politically inflected. Randolph, for instance, cited the administration’s concern that “unilateral regulation of U.S. motor-vehicle emissions could weaken efforts to persuade developing countries to reduce the intensity of greenhouse gases thrown off by their economies.” Doniger countered that the issue of geopolitical bargaining chips had nothing to do with the case, also adding, “This is a laughable argument. The one thing that would encourage developing countries to act is a little leadership from the world’s largest polluter.”

Randolph also cited concerns that “piecemeal” regulation of CO2 from vehicles would not cover other polluting industries, implying that this would pose an unfair disadvantage to automakers. Doniger stressed that the law applies to any source of pollution that “causes or contributes” to the problem, and does not stipulate the inclusion of all sources.

Sentelle’s reasoning was similarly far-flung, according to enviros. “He concluded that the petitioning states, cities, and environmental organizations lack standing to sue over global-warming pollution,” explained Doniger. “He said that because global warming is ‘harmful to humanity at large,’ no one can go to court. That’s an absurd result, leaving no judicial remedies against illegal government action.”

Though Randolph and Sentelle effectively determined that EPA was not obligated to regulate CO2 under the Clean Air Act, their opinions never addressed directly the question of whether the act gives the agency the authority to do so.

The dissenting judge, David Tatel, spoke to the issue head-on when he came down strongly on the side of the plaintiffs in his written opinion: “I have grave difficulty seeing how EPA … could possibly fail to conclude that global warming ‘may reasonably be anticipated to endanger public health or welfare.'” He added that “EPA has authority — indeed the obligation” — to regulate greenhouse-gas emissions from motor vehicles.

Because the case ultimately left this question of authority undecided, say enviros, it will not impede the efforts of California and other states to adopt their own limits on CO2 emissions from motor vehicles.

According to Doniger, Tatel’s 38-page opinion is strong encouragement to appeal the decision. Doniger was optimistic that the coalition of green groups and attorneys general from states including California, Illinois, and Massachusetts would “seek a re-hearing before the full 11-member U.S. Court of Appeals, or we will take it to the Supreme Court.”