A few minutes ago, the Supreme Court ruled 5-4 in Utility Air Regulatory Group v. EPA that the Environmental Protection Agency unreasonably refused to consider the economic costs of its regulatory zeal in deciding to regulate electric utilities. Justice Scalia, writing for the majority, held that “appropriate and necessary” – the standard governing the agency’s decisionmaking – requires agencies to do some balancing: “One would not say that it is even rational, never mind ‘appropriate,’ to impose billions of dollars in economic costs in return for a few dollars in health or environmental benefits.” Moreover, “[n]o regulation is ‘appropriate’ if it does significantly more harm than good.” Also: “Chevron allows agencies to choose among competing reasonable interpretations of a statute; it does not license interpretive gerrymanders under which an agency keeps parts of statutory context it likes while throwing away parts it does not.” (Justice Thomas’s opinion also strikes a blow against Chevron deference.)