National Mining Association v. United States Environmental Protection Agency

In 1990, Congress revised the regulation of emissions of hazardous air pollutants under § 112 of the Clean Air Act (CAA). Congress’s amendments in § 112 replaced the Environmental Protection Agency’s (EPA) (defendant) health-based regulation of pollutants with a technology-based regulatory scheme. Congress required the EPA to publish a list of major sources and area sources that emitted certain pollutants and promulgate emissions standards for each. Major sources were defined by the rule as a group of stationary sources that were in a contiguous area and under common control and, in the aggregate, emit or, considering controls, have the potential to emit, 10 tons per year or more of any hazardous air pollutant or 25 tons per year of any combination of hazardous air pollutants. The EPA included fugitive emissions in its calculation. A stationary source was defined as any building that emits or may emit any air pollutant. An area source was any stationary source that was not a major source. The EPA defined a source’s potential to emit as the source’s maximum capacity to emit a pollutant under its physical and operational design, accounting for operational restraints that were federally enforceable. Federally enforceable controls were those that had been approved by the EPA and integrated into the state implementation plan that was drawn up by each state to enforce CAA restrictions. The EPA would not consider limitations other than those that were federally enforceable. National Mining Association and other industrial companies (NMA) (plaintiffs) challenged the EPA’s inclusion of fugitive emissions in making major source determinations because it had been held that under § 302 of the CAA, the EPA could not include fugitive emissions when determining whether a source was a major stationary source based on direct emissions. NMA also argued that the EPA may not make major source determinations without separating the facilities by industrial classification. Chemical Manufacturing Association and American Petroleum Institute (CMA) (plaintiffs) claimed that the EPA overstepped its regulatory authority by only permitting sources to reduce emissions using federally enforceable emissions controls and limitations.