The Environmental Protection Agency had no right to halt enforcement of a methane reduction rule imposed during the Obama Administration, a federal court ruled this week.

The U.S Court of Appeals for the District of Columbia found that EPA Administrator Scott Pruitt had no authority under the Clean Air Act to suspend the rule without a formal rulemaking process and public comment period.

The methane rule was enacted in May 2016 with the goal of reducing methane gas emissions to nearly half of 2012 levels.

The performance standard establishes new source performance standards for greenhouse gas emissions and volatile organic compound emissions from the oil and natural gas sector. Among the requirements was to detect and repair leaks of methane and other pollutants, certifying those fixes by a professional engineer.

In an April 18 letter to oil and gas companies, the EPA, under Pruitt’s direction, reported that it would reconsider the fugitive emission requirements. The agency later issued a 90-day stay to halt federal leak detection and repair requirements scheduled to take full effect on June 3.

Pruitt suggested that he would also propose to extend the stay indefinitely

In response, environmental activists, led by the Natural Resources Defense Council, promised to “sue as the Trump Administration begins dismantling methane pollution protections.”

NRDC is an international nonprofit environmental organization with more than 2 million members and online activists.

 “Leak detection and repair is crucial to identify and stop methane and other pollutants from pouring out of the hundreds of valves, pumps, tanks and other equipment at oil and gas wells, as well as in the pipeline network that brings the gas to market,” it said in a statement. “Finding and fixing these leaks is technically simple, cost-effective, prevents wasted gas, and creates high-paying jobs.”

A group of 16 states and cities joined the subsequent litigation against the EPA’s decision.

The court granted the request for an emergency stay. “We conclude that EPA lacked authority under the Clean Air Act to stay the rule, and we therefore grant petitioners’ motion to vacate the stay,” the majority opinion says.

“By staying the methane rule, the EPA… has also suspended the rule’s compliance deadlines. EPA’s stay, in other words, is essentially an order delaying the rule’s effective date, and this court has held that such orders are tantamount to amending or revoking a rule,” the opinion says.

“The court’s decision means that oil and gas facilities will have to undertake commonsense leak detection and repair measures, reducing the harmful pollution our children and families will breathe this summer,” says EDF General Counsel Vickie Patton.