The entire gamut of judicial responses to precautionary administrative action aimed at potential environmental threats to public health marked the D.C. Circuit's recent en banc decision¹ upholding the Environmental Protection Agency's 1973 regulations requiringprogressive phasing out of gasoline lead additives in the interests of public health. The closeness of the vote,² the depth of the differences between court majority and minority, and the lengths to which each side went to develop its arguments,³ all underscore the difficulties that the judiciary continues to have in reviewing future-oriented administrative action, even when supported by the relatively specific precautionary statutory authority of the Clean Air Act. And it is only by going to great lengths to minimize the uniqueness of the kind of risk assessment and uncertain prediction engaged in by the EPA Administrator in regulating lead that Judge Wright's opinion for the majority makes a beginning at incorporating such actions within the parameters of normal judicial review.

At issue was the Administrator's decision to promulgate regulations phasing out automotive lead additives under §211(c)(1)(A) of the Clean Air Amendments of 1970 (CAA).⁴ More specifically, the dispute centered around (1) EPA's interpretation of the statutory term "will endanger public health or welfare," which sets the threshold determination to be made before the Administrator can regulate fuel additives; (2) the adequacy of EPA's data base of scientific and medical studies to support its conclusion that airborne lead from automobile emissions presents a "serious risk of harm" to a significant portion of the urban public and a large fraction of urban children; (3) the proper scope and method of judicial review under the arbitrary and capricious standard as interpreted by the Supreme Court in Citizens to Preserve Overton Park v. Volpe,⁵ and (4) the procedural propriety of the manner in which the EPA promulgated the final regulations and their supporting data base. The court majority and minority were totally at odds over all these issues.