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MICHIGAN v. EPA KAGAN, J., dissenting
deliberated on and then set emissions limits, costs came into the calculus at nearly every turn. Reflecting that consideration, EPA’s final rule noted that steps taken during the regulatory process had focused on “flexib[ility] and cost-effective[ness]” and had succeeded in making “the rule less costly and compliance more readily manageable.” 77 Fed. Reg. 9306, 9376. And the regulation concluded that “the benefits of th[e] rule” to public health and the environment “far outweigh the costs.” Id., at 9306. Consistent with the statutory framework, EPA initially calculated floor standards: emissions levels of the bestperforming 12% of power plants in a given category or subcategory. The majority misperceives this part of the rulemaking process. It insists that EPA “must promulgate certain . . . floor standards no matter the cost.” Ante, at 11. But that ignores two crucial features of the top-12% limits: first, the way in which any such standard intrinsically accounts for costs, and second, the way in which the Agency’s categorization decisions yield different standards for plants with different cost structures. The initial point is a fact of life in a market economy: Costs necessarily play a role in any standard that uses power plants’ existing emissions levels as a benchmark. After all, the best-performing 12% of power plants must have considered costs in arriving at their emissions outputs; that is how profit-seeking enterprises make decisions. And in doing so, they must have selected achievable levels; else, they would have gone out of business. (The same would be true even if other regulations influenced some of those choices, as the majority casually speculates. See ante, at 13.) Indeed, this automatic accounting for costs is why Congress adopted a market-leader-based standard. As the Senate Report accompanying the 1990 amendments explained: “Cost considerations are reflected in the selection of emissions limitations which have been achieved in practice (rather than those which are merely
