The Supreme Court declined to block two key Environmental Protection Agency (EPA) regulations on Friday in a blow to red states and industry interests challenging the rules.

The court did not intervene to pause the EPA’s rules tightening limits for mercury in coal-fired power plant emissions and methane generated by oil and gas production, meaning that the rules are clear to take effect while the challengers’ litigation works its way through lower courts, according to Reuters. The organizations and states that filed the emergency appeals to the Supreme Court have argued that the agency overstepped its legal authority in issuing the regulations under the Clean Air Act and that EPA is depriving states of their ability to establish their own emissions rules.

The mercury regulations would reduce the amount of toxic metals that all coal-fired power plants are allowed to emit by 67% and would tighten limits on lignite coal plants’ mercury emissions by 70%, according to Reuters. Challengers — which include oil and gas developers, mining companies and groups focused on power markets — argued that the EPA overreached in issuing the new limits and that the regulation will jeopardize America’s energy reliability by effectively forcing the premature retirement of coal-fired power plants.

‘Inevitable And Foreseeable’: Grid Operators Beg Court To Nix EPA Rules To Save Electricity System From Collapsehttps://t.co/0LAt8gHVSN

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The methane rules, which also pertain to a type of emissions called “volatile organic compounds,” are designed to limit flaring, or burning off extra methane during the process of producing oil and gas, according to Reuters. The rules would also require developers to more closely monitor potential methane leaks from their oil and gas infrastructure, as well as establish a methane leak reporting program specifically for methane “super-polluters.”

“EPA is pleased that the Supreme Court has denied the applications for a stay of the revised Mercury and Air Toxics Standards (MATS),” an EPA spokesperson said in a statement shared with the Daily Caller News Foundation. “The Agency believes the revised MATS rule, which will ensure that the nation’s coal-fired power plants meet up-to-date standards for hazardous air pollutants that reflect the latest advancements in pollution control technologies, is firmly grounded in its Clean Air Act authority.”

The U.S. Court of Appeals for the D.C. Circuit declined in July and August to temporarily block the two rules while it reviews them, according to Reuters.

The Supreme Court has taken action to block major regulatory moves by the EPA in recent years, such as its landmark 2022 ruling in West Virginia v. EPA that vacated the agency’s 2014 “Clean Power Plan” to reshape the American power grid to heavily rely on green energy instead of fossil fuels.

In June, the court also struck down “Chevron deference,” a precedent that formerly allowed agencies like the EPA broad discretion to interpret ambiguous statutes. That particular ruling is already teeing up challenges to some of the most aggressive regulatory actions taken to date by the Biden-Harris EPA.

Editor’s note: This article has been updated to include comment from the EPA.

(Featured Image Media Credit: Flickr/Tony Webster)