The U.S. Environmental Protection Agency’s (EPA’s) Mercury and Air Toxics Standards (MATS) have been seen by many in the coal-fired power industry as potentially more expensive and onerous than its Clean Power Plan, which addresses greenhouse gases. On Nov. 25, the Supreme Court agreed to review a consolidated case that could potentially prevent the MATS rule from going into effect.

The Court will review an April 15 decision by the Court of Appeals for the District of Columbia Circuit that upheld MATS, which was finalized in February 2012.

The Court is consolidating three cases (Michigan, et al. v. EPA, et al., Utility Air Regulatory Group v. EPA, et al., and National Mining Assoc. v. EPA, et al.), limiting oral arguments to one hour, and focusing on a limited question: “Whether the Environmental Protection Agency unreasonably refused to consider costs in determining whether it is appropriate to regulate hazardous air pollutants emitted by electric utilities.” A ruling is due in June.

Just last week, the EPA issued changes to startup and shutdown provisions related to MATS.

In the meantime, many generators have already evaluated and even adopted new or revised environmental controls in order to comply with MATS. In April, the Energy Information Administration reported that at least 70% of U.S. coal-fired generating capacity had already installed environmental control equipment to comply with the rule.

Gail Reitenbach, PhD, Editor (@GailReit, @POWERmagazine)