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MICHIGAN v. EPA KAGAN, J., dissenting
And that is exactly what EPA did over the course of its rulemaking process, insisting on apples-to-apples comparisons that bring floor standards within reach of diverse kinds of power plants. Even in making its “appropriate and necessary” finding, the Agency announced it would divide plants into the two categories mentioned above: “coal-fired” and “oil-fired.” 65 Fed. Reg. 79830.3 Then, as the rulemaking progressed, EPA went further. Noting that different technologies significantly affect the ease of attaining a given emissions level, the Agency’s proposed rule subdivided those two classes into five: plants designed to burn high-rank coal; plants designed to burn low-rank virgin coal; plants that run on a technology termed integrated gasification combined cycle; liquid oil units; and solid oil units. See 76 Fed. Reg. 25036–25037. EPA explained that by subcategorizing in that way, it had spared many plants the need to “retrofit[ ],” “redesign[ ],” or make other “extensive changes” to their facilities. Id., at 25036. And in its final rule, EPA further refined its groupings in ways that eased compliance. Most notably, the Agency established a separate subcategory, and attendant (less stringent) floor, for plants in Hawaii, Puerto Rico, Guam, and the Virgin Islands on the ground that plants in those places have “minimal control over the quality of available fuel[ ] and disproportionately high operational and maintenance costs.” 77 Fed. Reg. 9401.4 —————— 3 EPA
also determined at that stage that it is “not appropriate or necessary” to regulate natural gas plants’ emissions of hazardous air pollutants because they have only “negligible” impacts. 65 Fed. Reg. 79831. That decision meant that other plants would not have to match their cleaner natural gas counterparts, thus making the floor standards EPA established that much less costly to achieve. 4 The majority insists on disregarding how EPA’s categorization decisions made floor standards less costly for various power plants to achieve, citing the Agency’s statement that “it is not appropriate to premise subcategorization on costs.” 77 Fed. Reg. 9395 (quoted ante, at 13). But that misunderstands EPA’s point. It is quite true that EPA
