The D.C. Circuit Court of Appeals has severed challenges to the U.S. Environmental Protection Agency’s (EPA’s) mercury and air toxics standards for power plants by separating arguments over the agency’s new source performance standards (NSPS) from other challenges to the regulations White Stallion Energy Ctr., LLC v. EPA, No. 12-1100 (D.C. Cir. 8/24/12). The decision followed the request of the Utility Regulatory Group, a powerplant trade association, that the court sever its legal challenges to the mercury and air toxics standards and hold that challenge in abeyance. The group argued that separating and delaying the performance standard challenge would provide EPA an opportunity to address its petition for reconsideration. Although the court agreed to separate those issues from other challenges to the power-plant rule, it declined to hold the performance standard challenges in abeyance.

EPA issued its mercury and air toxics standards for new coal-fired power plants in December 2011. The rule sets numeric emissions limits for mercury, filterable particulate matter as a surrogate for toxic metals, and hydrogen chloride as a surrogate for acid gases. The final rule also revised NSPS for power plants to address emissions of particulate matter, sulfur dioxide and nitrogen oxides. 77 Fed. Reg. 9,304 (12/22/11). Under the court’s order, the D.C. Circuit will hear three separate challenges to EPA’s mercury and air toxics standards for power plants, and all of the legal arguments will be heard on the same day.