The EPA wants to regulate carbon emissions from power plants under the same rule it uses to regulate emissions from cars. Jeff Swensen/Getty Images

The Supreme Court on Monday scrutinized the scope of the Environmental Protection Agency in a case with a narrow focus but with the potential to touch on the very purpose of the regulator and the use of executive action by President Barack Obama.

The case — Utility Air Regulatory Group v. EPA — examines six challenges brought by various industry groups and conservative politicians against the EPA for what they see as regulatory overreach.

The plaintiffs say they hope the Supreme Court justices will answer questions that get to the heart of the function of the EPA, like whether the agency has the right to freely interpret the Clean Air Act without the consent of Congress and even whether the EPA has the right to regulate carbon dioxide as a polluting gas at all.

But the court may skirt those thornier questions in favor of narrower ones — deciding whether the EPA can regulate greenhouse gases from power plants, big factories and other stationary sources of emissions under the same authority it has used to regulate new motor vehicles and whether the agency may unilaterally raise the amount a stationary source is allowed to emit before the EPA can regulate it.

Experts say that no matter what the court rules, the EPA will likely still be able to impose permitting requirements and limits on emissions for stationary sources.

Despite the likelihood of the Supreme Court hearing’s limited scope, the case has become a catch-all for criticism of the EPA, which some conservatives see as a rogue agency, overstepping constitutional protections for free enterprise and carrying out the whims of a president who has stated he will take progressive actions “with or without Congress.”

“This case involves perhaps the most audacious seizure of pure legislative power over domestic economic matters attempted by the executive branch” since President Harry S. Truman tried to control U.S. steel companies during the Korean War, a brief signed by Rep. Michele Bachmann and other politicians read.

Many conservatives take particular issue with the EPA’s interpretation of the Clean Air Act — which was passed in 1963, decades before carbon dioxide was considered a pollutant — to make it easier to regulate carbon pollution. Specifically, the agency wants to change the amount emitted per year before a source falls under its purview, from 100 tons to 75,000 or 100,000 tons. Otherwise, the agency says, it would have to start regulating the emissions of not only power plants but also schools, hospitals and residential buildings.

“EPA’s tailoring rule is one of the most brazen power grabs ever attempted by an administrative agency,” read a brief filed by Greg Abbott, the attorney general of Texas. “Rather than apply the unambiguous permitting requirements that the act establishes for all air pollutants … (the rule) invents its own thresholds for CO2.”

But the plaintiffs’ heated language may be mismatched with what’s actually at stake in this case, energy and environmental law experts say.

“Even if EPA loses, I don’t see this as having a huge impact on what they do,” said Shelley Welton, deputy director at the Center for Climate Change Law at Columbia Law School. “Whether or not the court decides this specific regulation allows them to regulate power plants, they’ll still be able to go forward (with regulation) in other ways.”

Nonetheless, the case may have ramifications beyond the letter of the law.

Obama has used executive actions to push through gun control measures and raise the minimum wage for federal contractors, and in his State of the Union, he said he plans to use more to bypass a perpetually gridlocked Congress.

The EPA’s attempt to regulate carbon from stationary sources isn’t part of an executive order, but it has given Obama’s critics fuel for their arguments that Obama has gone too far in implementing and interpreting laws without the consent of Congress.

“I see this case as a big deal politically more than legally,” said Amanda Leiter, an environmental law professor at American University. “Industry groups could use a win to make the argument that the EPA is overreaching, much as they’ve said about ‘Obamacare.’ So if the administration loses, they lose some public good will.”

Experts warn that as Obama and the EPA continue to move without Congress, courts may see more cases like this in the near future.

“Executive action is Obama’s only tool right now,” Welton said. “This is the new normal until we see an administration that doesn’t have the environment as a priority or a Congress that isn’t at a standstill.”