ELR Citation: ELR 20148
No(s). 03-1361 (D.C. Cir. Jul 15, 2005)

The court upheld the U.S. Environmental Protection Agency's (EPA's) denial of a petition asking it to regulate carbon dioxide and other greenhouse gas (GHG) emissions from motor vehicles under the Clean Air Act (CAA). CAA §202(a)(1) directs the Administrator to regulate emissions that "in his judgment" "may reasonably be anticipated to endanger public health or welfare." Thus, §202(a)(1) gives the Administrator considerable discretion. As the court previously found in Ethyl Corp. v. EPA, 541 F.2d 1, 6 ELR 20267 (D.C. Cir. 1976), the Administrator need not exercise his discretion solely on the basis of his assessment of scientific evidence; rather, "policy judgments" also may be taken into account. Moreover, a determination of endangerment to public health "is necessarily a question of policy that is to be based on an assessment of risks and that should not be bound by either the procedural or the substantive rigor proper for questions of fact." Here, in addition to the scientific uncertainty about the causal effects of GHGs on the future climate of the earth, the Administrator relied on many policy considerations which, in his judgment, warranted regulatory forebearance at this time. And, as the court held in Environmental Defense Fund v. EPA, 598 F.2d 62, 8 ELR 20765 (D.C. Cir. 1978), a reviewing court "will uphold agency conclusions based on policy judgments" when dealing with issues on the "frontiers of scientific knowledge."