Environmental Protection Agency et al. v. EME Homer City Generation, L.P., et al. (2014) __U.S.__ (April 29, 2014, Case no. 12-1182)

Over the past several decades, Congress and the Environmental Protection Agency (EPA) have made several efforts to address the difficult challenge of curtailing air pollution emitted in upwind states, but causing harm in downwind states. Under the Clean Air Act, the EPA must establish national ambient air quality standards (NAAQS) for pollutants at levels that will protect health. Once the EPA establishes a NAAQS, it must designate “nonattainment” areas—locations where pollution concentration exceeds the NAAQS. Within three years of any new or revised NAAQS, each state must submit a State Implementation Plan (SIP) to achieve the NAAQS. If the EPA determines a SIP is inadequate, it must prepare and adopt a Federal Implementation Plan (FIP). Among other things, the SIP must “contain adequate provisions … prohibiting … any source or other type of emissions activity within the State from emitting any air pollutant in amounts which will … contribute significantly to nonattainment in, or interfere with maintenance by, any other State with respect to any … [NAAQS].” (42 U.S.C. § 7410 (a)(2)(D)(i).) This requirement is known as the “Good Neighbor Provision” of the Clean Air Act.

Many times over the past two decades, the EPA has attempted to delineate the Good Neighbor Provision’s scope by identifying under what circumstances an upwind state can be said to “contribute significantly” to nonattainment in downwind states. One such attempt is the EPA’s Cross-State Air Pollution Rule (Transport Rule), which aims to reduce mono-nitrogen oxides (NO_x) and sulfur dioxide (SO₂) emissions in 27 upwind states to achieve attainment of three NAAQS in downwind states. Under the Transport Rule, an upwind state “contribute[s] significantly” to downwind nonattainment if its exported pollution: (1) produces one percent or more of a NAAQS in at least one downwind state; and (2) could be eliminated cost-effectively, as determined by the EPA. Upwind states whose emissions meet both these criteria must eliminate their emissions. Based on complex modeling, the EPA also created an annual emission “budget” for each of the regulated upwind states, representing the total quantity of pollution an upwind state may produce in a given year under the Transport Rule. Having determined that each of the regulated upwind states’ SIPs was inadequate, the EPA also adopted FIPs concurrently with its adoption of the Transport Rule.

A group of state and local governments, joined by industry and labor groups, petitioned for review of the Transport Rule in the D.C. Circuit. The Court of Appeal vacated the rule in its entirety, holding that: (1) the EPA must give states a reasonable opportunity to allocate their emission budgets before issuing the FIPs; and (2) the EPA must not consider cost in determining whether an upwind state “contribute[s] significantly” to a downwind state’s nonattainment. In an opinion delivered by Justice Ginsburg, in which Justices Roberts, Kennedy, Breyer, Sotomayor, and Kagan joined, the Supreme Court reversed.

First, the Court held that the Clean Air Act does not require the EPA to give states a second chance to file a SIP after the EPA has quantified the state’s interstate pollution obligations. Although the state respondents in the case did not challenge EPA’s disapproval of any particular SIP, they argued that the EPA is nevertheless required to give upwind states an additional opportunity to promulgate adequate SIPs after the EPA has set the state’s emission budgets. The Court found that the Clean Air Act’s plain text does not support this argument. Rather, the Clean Air Act only requires that once the EPA disapproves of a SIP, the EPA must issue a FIP. Although the EPA had previously provided upwind states an opportunity to allocate emission budgets among their in-state sources, this did not mean that the EPA acted arbitrarily in declining to do so here.

Second, the Court held that EPA’s cost-effective allocation of emission reductions among upwind states is a permissible, workable, and equitable interpretation of the Good Neighbor Provision. The Court noted that the Good Neighbor Provision does not dictate a specific method of apportioning responsibility among the upwind contributors. In the absence of specific guidance, the EPA’s use of costs in the Transport Rule is an efficient and equitable solution to the allocation problem presented by the Good Neighbor Provision. Furthermore, contrary to the D.C. Circuit’s holding, the EPA must have leeway in fulfilling its mandate to maximize achievement of attainment in downwind states.