Twelve US coal mining states, including West Virginia, Alabama, Indiana, Kansas, Kentucky, Louisiana, Nebraska, Ohio, Oklahoma, South Carolina, South Dakota, and Wyoming, have called on the District of Columbia Circuit Court of Appeals to invalidate the Environmental Protection Agency's recently-proposed regulations of carbon emissions from existing coal plants.

 In particular, the states are challenging the legality of the US government's 2011 settlement with three environmental organizations and another group of states, in which the EPA proposed to regulate carbon.

Without the court's prompt intervention, the petitioners say they will be forced to undertake "burdensome measures in the coming months to meet the demands of the unlawful rule."

This is the second attempt by some of the states to nullify the EPA's rules through the courts. Last month, nine joined forces with coal producer Murray Energy to sue the EPA, arguing it has no legal authority to regulate coal facilities under the Clean Air Act.

Murray Energy's CEO has claimed the agency is "lying about the existence of climate change", contending that the earth is actually cooling.

The states contend also that general air pollution from coal plants is already regulated under the act, so that greenhouse gas rules "impose impermissible double regulation."

Observers point out, however, that the US Supreme Court has already affirmed numerous times that the EPA is allowed to regulate greenhouse gases under the Clean Air Act.

US political pundits note also that the proposed regulations are far from being finalized, so that the lawsuit could be held as untimely. They add that the action appears designed primarily to score political points in the upcoming US midterm elections.