Dive Brief:

• The U.S. Environmental Protection Agency has asked the D.C. Circuit Court of Appeals to delay oral arguments scheduled for next month on the Mercury and Air Toxics Standards (MATS) as it reviews the rules governing harmful air pollution from coal plants. The federal government was scheduled to defend the rule. 
• The request from President Trump's administration mirrors others taken on Obama-era environmental rules, including plans to review the Clean Power Plan and the Waters of the United States (WOTUS) rule. The White House put each of those rules under review, and is expected to scale back or eliminate them.
• In 2015, the U.S. Supreme Court ruled the EPA did not properly consider costs as it wrote the MATS rule, but allowed it to stay in force as the agency went back to make changes. 15 states joined generators and coal companies in challenging the rule again, leading to the D.C. Circuit hearing in question. 

Dive Insight:

The MATS rule has been in effect for years and the power sector has largely complied with its limits on mercury emissions and other harmful pollutants.

But is still under challenge from more than a dozen states, including Oklahoma, whose challenge was filed by current EPA Administrator Scott Pruitt when he was the state's attorney general.

The EPA's court filing signals a change of position on the mercury limits, which the agency previously found would save thousands of lives per years.

"In light of the recent change in Administration, EPA requests continuance of the oral argument to give the appropriate officials adequate time to fully review" the rule, the agency said in its motion.

The agency intends to "closely review" the findings of health benefits from the MATS rule, and said EPA's prior positions "may not necessarily reflect its ultimate conclusions after that review is complete."

The move is the latest in a systematic campaign by the Trump Administration to roll back environmental rules put in place by President Obama.

Last month the agency announced it would review the Clean Power Plan, which aims to cut emissions from existing power plants 32% by 2030. And earlier this month the Supreme Court declined a request to stay litigation over the Waters of the United States rule, which the White House asked for as it reconsiders that rule as well.

Overturning MATS, however, may be a difficult challenge. James Pew, an attorney for Earthjustice, told the Washington Post that it would require finding the change would not have health impacts. “There’s no way it could ever make that showing when it comes to power plants,” he told the paper.

The Supreme Court has also already weighed in on the issue. In 2015, the court ruled that EPA had not considered costs at the proper time during the drafting of the MATS rule, but the ruling focused on procedural rulemaking issues, and the court allowed the regulations to stay in force for the power sector as the EPA revised its cost findings. 

Opponents of the MATS rule say it is unreasonable and is forcing coal plants offline. About 200 plants were granted one-year extensions to the compliance deadline in 2015, but most have made upgrades or gone offline.