A federal appeals court handed President Donald Trump's deregulatory agenda a major defeat on Monday by rejecting the administration's effort to halt an Obama-era rule aimed at reducing methane leaks, which have a powerful warming effect on the environment.

"People—particularly children—whose well-being, health, and even lives depend on these pollution limits, are today protected from a Government that seems hell-bent on rolling back these and other basic safeguards."
—Lauren Pagel, EarthworksThe attempt to delay the implementation of the rule—an effort led by Scott Pruitt, the head of the Environmental Protection Agency (EPA)—was deemed (pdf) by the U.S. Court of Appeals for the District of Columbia Circuit "arbitrary," "capricious," and "tantamount to amending or revoking a rule." On these grounds, the administration's bid was dismissed.

"The court's ruling came in response to a lawsuit filed June 5 by green groups that opposed the EPA's stay of the rule," Reuters noted. "The groups, including the Natural Resources Defense Council, Environmental Defense Fund, Sierra Club and other environmental organizations, argued the EPA did not follow procedures detailed in the 1970 law known as the Clean Air Act when it froze the rule."

Pruitt's announcement earlier this month that his agency would move to postpone the implementation of the methane rule sparked immediate reaction from scientists and environmentalists, who argued that methane "seriously and urgently threatens our climate, our pocketbook, and public health."

Given the risks methane poses, the court's ruling on Monday was met with applause and characterized as a "huge" victory for the planet and the public.

"This is a big win for public health and a wake-up call for this administration," Tim Ballo, an attorney at Earthjustice, said in a statement. "While Scott Pruitt and Donald Trump continue to bend over backwards to do the bidding of Big Oil, Earthjustice and our clients and partners will use every tool at our disposal to hold them fully accountable for their actions."

During his tenure as EPA chief, Pruitt has moved at a torrid pace to dismantle Obama-era regulations aimed at combating climate change. Since his confirmation, the New York Times reported on Sunday, Pruitt has attempted to undercut "more than 30 environmental rules, a regulatory rollback larger in scope than any other over so short a time in the agency's 47-year history."

In one instance, the Times noted, Pruitt acknowledged that delaying rules intended to limit methane leaks could "have a disproportionate effect on children."

"But he also said the rules would come at a significant cost to the oil and gas industry," the Times concluded. So he moved to delay the rules.

Some analysts have argued optimistically that Monday's ruling could be evidence that Pruitt will fail in his ultimate goal of freeing fossil fuel companies from regulatory restraint.

Rebecca Leber of Mother Jones wrote that the court's decision could be an "early preview of how Trump could fail to undo final EPA reg[ulations]."

Big @EPAScottPruitt court losses/retreats in: (1) mercury dental rule; (2) pesticides endangered species case; & (3) oil & gas methane rule.

— John Walke (@jwalkenrdc) July 3, 2017

In a statement celebrating the ruling, Lauren Pagel, policy director for Earthworks, said the court's "decision affirms we are a nation of laws and neither President Trump nor Administrator Pruitt can capriciously change that to benefit fossil fuel interests."

"People—particularly children—whose well-being, health, and even lives depend on these pollution limits, are today protected from a Government that seems hell-bent on rolling back these and other basic safeguards," Pagel concluded.