Supreme Court lets stand rules to curb mercury, methane emissions

The court, without comment, rejected a request by industry groups and Republican state attorneys general who had asked for the Environmental Protection Agency (EPA) rules to be put on hold while litigation continues in lower courts.

The EPA regulations, brought under the Clean Air Act, are designed to limit emissions of mercury and other toxic air pollutants from coal-fired power plants and curb emissions of methane -- a super-pollutant greenhouse gas -- from oil and gas facilities.

They are being challenged by power and mining companies and oil and gas firms who contend they are unnecessary and costly.

The nonprofit National Resources Defense Council (NRDC) welcomed the Supreme Court move allowing the EPA rules to remain in place for now.

"The Supreme Court has sensibly rejected two efforts by industry to halt critical safeguards," David Doniger, a senior attorney at the NRDC, said in a statement.

"For far too long, oil and gas producers have been allowed to ignore the leaks in their own equipment and let dangerous methane and smog-forming compounds pollute our air," Doniger said.

In June, the Supreme Court temporarily blocked the implementation of an EPA measure aimed at curbing air pollution that drifts across state lines from facilities like power plants.

The "good neighbor" plan would not have taken effect until 2026, but a series of states and companies requested that it be blocked now while litigation against it plays out in a lower court -- a request the Supreme Court granted in a 5-4 decision.

The court's decision to temporarily block the plan was the third time in recent years that it has curbed the EPA's powers, after it dealt a blow to the agency's authority to regulate wetlands in 2023 and greenhouse gases in 2022.