The five environmental cases in the 2006-2007 term were a varied lot: two involving the Clean Air Act, one the Superfund Act, one the relationship between the Clean Water Act and Endangered Species Act, and one the federal constitutional limits on local solid-waste "flow control." On the merits, the Court held that CAA section 202 empowers EPA to regulate emissions from new motor vehicles based on their global warming impacts, the statute being "unambiguous" on this score. The dispute centers on how to measure the emissions from a stationary source of emissions so as to determine whether a physical or operational change in that source "increases the amount," in the CAA's words, of emissions. However, the district court held that those regulations impose an hourly standard. Two scenarios may occur. In either case, the liable party, if made to pay more than its fair share, may turn around and sue other parties made liable by CERCLA in a "contribution" action. And §107(a) permits cost recovery (as distinct from contribution) by a private party that has itself incurred cleanup costs." This case arose from EPA's ultimate position, in connection with Arizona's request for delegation of the permit program, that EPA's decision was not subject to ESA consultation. Flow control ordinances typically require that all waste generated within a locality be taken to a locally designated transfer or disposal facility. The question was, does this public-private distinction make a difference to the dormant commerce clause analysis?
The Supreme Court decided five environmental cases during its 2006-2007 term, a significant proportion of the 72 cases it heard. Two decisions involve the Clean Air Act: one ruling that the act allows the Environmental Protection Agency (EPA) to regulate vehicle emissions based on their global warming impacts; the other, that EPA regulations validly impose an annual, as opposed to hourly, emissions change test in determining whether a modification of a stationary source makes it a "new source" requiring a permit. A Superfund Act decision held that liable parties who incur cleanup costs beyond their fair share may sue for reimbursement, despite another provision in the act restricting contribution actions. Another case dealt with the relationship between the Clean Water Act and Endangered Species Act, holding that the former's mandate that EPA "shall" delegate a permitting program to a state when statutory criteria are met is not subject to the equally unqualified command in the latter that consultation with federal wildlife-protection agencies occur. The remaining case involves a constitutional issue. It held that two counties' "flow control" laws, requiring that solid waste generated within the counties be taken to processing facilities within the counties, did not offend the Constitution's "dormant commerce clause" because the facilities were publicly owned.