Abstract: Whitman v. American Trucking Association was one of the most eagerly awaited regulatory decisions in many years. But the Court's understated, steady, lawyerly opinion was a bit of an anticlimax, representing a return to normalcy and leaving many open questions. The Court was correct to say that the relevant provision of the Clean Air Act forbids consideration of cost; it was also correct to refuse to invoke the nondelegation doctrine. Importantly, the Court left in place a set of important lower court decisions, allowing agencies to consider costs unless Congress expressly concludes otherwise. The Court also raised some new questions about the constitutional status of the Occupational Safety and Health Act. Perhaps most important, the Court has not ruled out nonconstitutional challenges to the particulates and ozone standards, or to ambient air quality standards generally. In suggesting that some of those challenges should succeed, especially against the new ozone regulation, this essay urges that Justice Breyer's concurring opinion in the case may well be the most influential in the future, because it fits most comfortably with other trends in the law of risk regulation, signaling the emergence of a kind of "cost-benefit state."