Page:Michigan v. EPA.pdf/45

 tion. In its "appropriate and necessary" finding, the Agency committed to exploring "least-cost solutions" in "developing a standard for utilities." 65 Fed. Reg. 79830. The Agency explained that such an approach—particularly mentioning the use of averaging and subcategorization— had offered "opportunit[ies] for lower cost solutions" and "helped build flexibility in meeting environmental objectives in the past." Ibid.; see supra, at 7, 18. Then, in issuing its proposed and final rules, EPA affirmed that it had done just what it said. EPA recognized that standardsetting must "allow the industry to make practical investment decisions that minimize costs." 76 Fed. Reg. 25057. Accordingly, the Agency said, it had "provid[ed] flexibility and compliance options" so as to make the rule "less costly" for regulated parties. 77 Fed. Reg. 9306. EPA added that it had rejected beyond-the-floor standards for almost all power plants because they would not be "reasonable after considering costs." Id., at 9331. And it showed the results of a formal analysis finding that the rule’s costs paled in comparison to its benefits. In sum, EPA concluded, it had made the final standards "cost efficient." Id., at 9434. What more would the majority have EPA say?

IV

IV Costs matter in regulation. But when Congress does not say how to take costs into account, agencies have broad discretion to make that judgment. Accord, ante, at 14 (noting that it is "up to the Agency to decide (as always, within the limits of reasonable interpretation) how to account for cost"). Far more than courts, agencies have the expertise and experience necessary to design regulatory processes suited to "a technical and complex arena." Chevron, 467 U. S., at 863. And in any event, Congress has entrusted such matters to them, not to us.

EPA exercised that authority reasonably and responsi-