But a separate EPA program to require greenhouse-gas permits for large industrial facilities will come under closer scrutiny. And it's not yet clear what a ruling on this program would mean.
Most of EPA's carbon rules stay intact
A quick recap: Back in 2007, the Supreme Court ruled that the EPA was required to regulate carbon-dioxide and other greenhouse gases under the Clean Air Act if it found that those gases posed a threat to human health and welfare (most scientists agree that they do).
Ever since then, the EPA has been busy regulating. The agency rolled out stricter fuel-economy standards for cars and light trucks, and it required large new facilities to adopt pollution-control technology as part of the permitting process. More recently, the EPA proposed carbon-dioxide limits for all future coal and natural gas power plants, with rules for existing plants coming soon.
The Supreme Court will leave much of this program intact. It won't review the EPA's "endangerment finding," which concluded that carbon-dioxide is a threat to human health. The Court also won't overturn the EPA's regulations of cars and light trucks. (These regulations have been challenged by industry groups.)
Instead, the court will consider the more narrow question of "whether EPA permissibly determined that its regulation of greenhouse gas emissions from new motor vehicles triggered permitting requirements under the Clean Air Act for stationary sources that emit greenhouse gases.”
What does that mean? Ever since 2011, the EPA has required anyone who wants to build or upgrade a large carbon-emitting facility — say, a power plant or refinery — to obtain permits for greenhouse gases and adopt certain pollution-reduction technologies. Industry groups and some states have argued that the EPA basically misinterpreted the Clean Air Act in requiring these permits. That's what's at issue here. (See Ann Carlson for much more technical detail.)
Will the Supreme Court's review matter much? Maybe!
Some legal experts think the dispute over permitting is fairly minor in the grand scheme of things. "The Supreme Court didn't grant cert to the questions that would have threatened the really significant EPA programs," argues Robert McKinstry, an environmental lawyer at Ballard Spahr.
For instance, McKinstry points out that the EPA's upcoming regulations for existing natural gas and coal power plants are being done under an entirely different section of the Clean Air Act.
Indeed, many environmental groups seemed relieved by the court's decision. "It means the way is clear to issue carbon pollution standards for power plants under the president’s Climate Action Plan," said David Doniger, policy director of the Natural Resources Defense Council, in a statement. "What the Supreme Court will review is one specific, narrow question."
Nathan Richardson, an expert in EPA regulation at Resources for the Future, agreed: "The most important [greenhouse-gas] regulations under the Act, standards for existing sources, will be similarly unaffected by any outcome of this case."
Critics of the EPA's carbon regulations, however, say the Supreme Court decision could turn out to be significant. "The question presented will force the Court to confront the consequences [of its 2007] decision," notes Jonathan Adler, a law professor at Case Western Reserve University. The permitting rules in question, he says, "expressly require the EPA (and state permitting authorities) to regulate more facilities than it could ever hope to have the resources to regulate."
And others think the case has the potential to be very important. Brian Potts, a lawyer specializing in environmental regulation at Foley & Lardner, says that the Supreme Court could in theory "gut EPA’s ability to regulate stationary sources like power plants." But, he adds, he thinks the EPA is on fairly solid legal footing with its permitting program.
"The Clean Air Act allows EPA to regulate 'any air pollutant' emitted from stationary sources," Potts explained in an e-mail. "The Supreme Court has already held that greenhouse gases are 'air pollutants.' Since at least 1978, EPA has interpreted the term 'any air pollutant' to mean 'any pollutant regulated under the Act.' As such, the Tailpipe Rule triggered stationary source regulation because - once adopted - greenhouse gases were regulated under the Act."
"The word 'any,' which EPA is interpreting, is obviously broad," Potts concluded. "I would be surprised if the Supreme Court sided with industry on this one."
Related: My colleague Juliet Eilperin has much more on the Supreme Court review.