Few environmental cases have received as much attention as American Trucking Ass'n v. U.S. Environmental Protection Agency,² recently argued before the U.S. Supreme Court. Even readers of the mainstream press³ are aware that industrial petitioners have urged the Court to inject cost-benefit considerations into the Clean Air Act (CAA) ambient air quality standard-setting process, and in effect overrule the 20-year Lead Industries Ass'n v. U.S. Environmental Protection Agency⁴ precedent of the D.C. Circuit.

Two little-noticed D.C. Circuit cases decided in the summer of 2000, however, have imposed at least some form of cost-benefit obligations on the U.S. Environmental Protection Agency (EPA) despite statutory silence on the issue. In both cases, the court vacated EPA rules on "reasoned decisionmaking" grounds, and said that cost-benefit factors should be evaluated by the Agency.