In 2012 the Environmental Protection Agency issued a Final Rule subjecting coal and oil-fired electric utility steam generating units, or EGUs, to EPA regulation under section 112 of the Clean Air Act, officially listing them as “source-categories” of Hazardous Air Pollutant, or HAP, emissions. Additionally, the agency held that situation-specific factors, such as implementation and compliance costs, should not be considered when designating EGUs for regulation. In White Stallion Energy Center, LLC v. U.S. Environmental Protection Agency, the U.S. Court of Appeals for the D.C. Circuit held that the CAA does not require EPA to consider implementation and compliance costs when designating coal and oil-fired EGUs for regulation. The legislative purpose and statutory language of CAA section 112, however, supports a finding that EPA is actually barred from such cost consideration. This Comment argues that in light of the D.C. Circuit’s holding in White Stallion, EPA could have interpreted section 112 in its 2012 Final Rule to completely prohibit the agency from considering EGU regulatory compliance costs. If EPA had taken a stronger position on the statutory bar to cost consideration, the D.C. Circuit would have affirmed the agency’s decision as the correct interpretation of section 112. Such a holding, in turn, would have ensured more environmentally friendly decision-making for years to come.