The case originated when a group of private organizations petitioned the Environmental Protection Agency (EPA) to begin regulating greenhouse gases, including carbon dioxide, under the Clean Air Act. The Clean Air Act requires that the EPA establish “standards applicable to the emission of any air pollutant from any class of new motor vehicles which...cause[s], or contribute[s] to, air pollution reasonably anticipated to endanger public heath or welfare.”

EPA denied the petition, reasoning that:

1. The Clean Air Act does not authorize it to issue mandatory regulations to address global climate change, and

2. Even if it did have the authority to set greenhouse gas emission standards, it would have been unwise to do so at that time because a causal link between greenhouse gases and the increase in global surface air temperatures was not unequivocally established.

The EPA also characterized any theoretical regulation of greenhouse gas emissions from motor vehicles as a piecemeal approach to climate change that would conflict with the Administration’s non-regulatory approach to encouraging reduction, among other factors.

The original petitioners, joined by Massachusetts and other state and local governments, sought review of the decision in the DC Circuit, which denied review in a 2-1 decision. The case moved to the Supreme Court, and was heard 29 Nov 2006. In the 5-4 decision today, the Court held that:

1. The Petitioners do in fact have standing to challenge the EPA’s denial of the rulemaking petition.

2. The harms associated with climate change are serious and well recognized.

   Indeed, the NRC Report itself, which EPA regards as an objective and independent assessment of the relevant science, identifies a number of environmental changes that have already inflicted significant harms, including the global retreat of mountain glaciers, reduction in snow-cover extent, the earlier spring melting of rivers and lakes, [and] the accelerated rate of rise of sea levels during the 20th century relative to the past few thousand years ...

3. EPA’s failure to dispute the existence of a causal connection between man-made greenhouse gas emissions and global warming, its refusal to regulate such emissions, at a minimum, “contributes” to Massachusetts’ injuries. EPA overstates its case in arguing that its decision not to regulate contributes so insignificantly to petitioners’ injuries that it cannot be haled into federal court, and that there is no realistic possibility that the relief sought would mitigate global climate change and remedy petitioners’ injuries, especially since predicted increases in emissions from China, India, and other developing nations will likely offset any marginal domestic decrease EPA regulation could bring about.

   ...EPA overstates its case. Its argument rests on the erroneous assumption that a small incremental step, because it is incremental, can never be attacked in a federal judicial forum. Yet accepting that premise would doom most challenges to regulatory action. Agencies, like legislatures, do not generally resolve massive problems in one fell regulatory swoop...They instead whittle away at them over time, refining their preferred approach as circumstances change and as they develop a more-nuanced understanding of how best to proceed.

   That a first step might be tentative does not by itself support the notion that federal courts lack jurisdiction to determine whether that step conforms to law.

   And reducing domestic automobile emissions is hardly a tentative step. Even leaving aside the other greenhouse gases, the United States transportation sector emits an enormous quantity of carbon dioxide into the atmosphere according to the MacCracken affidavit, more than 1.7 billion metric tons in 1999 alone. That accounts for more than 6% of worldwide carbon dioxide emissions.

   To put this in perspective: Considering just emissions from the transportation sector, which represent less than one-third of this country’s total carbon dioxide emissions, the United States would still rank as the third-largest emitter of carbon dioxide in the world, outpaced only by the European Union and China.  Judged by any standard, US motor-vehicle emissions make a meaningful contribution to greenhouse gas concentrations and hence, according to petitioners, to global warming.

4. While regulating motor-vehicle emissions may not by itself reverse global warming, it does not follow that the Court lacks jurisdiction to decide whether EPA has a duty to take steps to slow or reduce it.

   Because of the enormity of the potential consequences associated with man-made climate change, the fact that the effectiveness of a remedy might be delayed during the (relatively short) time it takes for a new motor-vehicle fleet to replace an older one is essentially irrelevant. Nor is it dispositive that developing countries such as China and India are poised to increase greenhouse gas emissions substantially over the next century: A reduction in domestic emissions would slow the pace of global emissions increases, no matter what happens elsewhere.

5. Despite an agency’s refusal to initiate enforcement proceedings not ordinarily being subject to judicial review, the Court held that it “may reverse [it if it finds it to be] arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law.”

6. Because greenhouse gases fit well within the Act’s capacious definition of “air pollutant,” EPA has statutory authority to regulate emission of such gases from new motor vehicles.

   Because EPA believes that Congress did not intend it to regulate substances that contribute to climate change, the agency maintains that carbon dioxide is not an air pollutant within the meaning of the provision. The statutory text forecloses EPA’s reading. The Clean Air Act’s sweeping definition of “air pollutant” includes “any air pollution agent or combination of such agents, including any physical, chemical ...substance or matter which is emitted into or otherwise enters the ambient air...§7602(g) (emphasis added). On its face, the definition embraces all airborne compounds of whatever stripe, and underscores that intent through the repeated use of the word “any.” Carbon dioxide, methane, nitrous oxide, and hydrofluorocarbons are without a doubt “physical [and] chemical...substance[s] which [are] emitted into...the ambient air.”  The statute is unambiguous.

7. EPA’s duty is to protect the public health and welfare, even if by setting standard in doing so, it overlaps with the responsibilities of other agencies.

   EPA finally argues that it cannot regulate carbon dioxide emissions from motor vehicles because doing so would require it to tighten mileage standards, a job (according to EPA) that Congress has assigned to DOT. But that DOT sets mileage standards in no way licenses EPA to shirk its environmental responsibilities. EPA has been charged with protecting the public’s “health” and “welfare,” a statutory obligation wholly independent of DOT’s mandate to promote energy efficiency. The two obligations may overlap, but there is no reason to think the two agencies cannot both administer their obligations and yet avoid inconsistency.

8. EPA’s alternative argument for its decision—that even if it had authority to regulate greenhouse gases, the timing was not good—is “divorced from the statutory text” and is “impermissible.”Its action was “arbitrary, capricious, or otherwise not in accordance with law.” EPA must reconsider its decision, and ground its reasons for action or inaction in the Clean Air Act statute.

Justice Stevens delivered the opinion of the Court, in which Justices Kennedy, Souter, Ginsburg, and Breyer joined. Chief Justice Roberts filed a dissenting opinion, in which Justices Scalia, Thomas, and Alito joined. Justice Scalia also filed a dissenting opinion, in which Chief Justice Roberts and Justices Thomas and Alito joined.

Reaction from the Alliance of Automobile Manufacturers was somewhat muted. In a statement concerning the decision, Alliance president and CEO Dave McCurdy said:

The Alliance of Automobile Manufacturers believes that there needs to be a national, federal, economy-wide approach to addressing greenhouse gases.  This decision says that the US Environmental Protection Agency will be part of this process. The Alliance looks forward to working constructively with both Congress and the administration, including EPA and the National Highway Traffic Safety Administration, in developing a national approach.

The Alliance is one of the groups supporting the challenge in court to California’s law regulating motor vehicle greenhouse gas emissions.

Resources:

• Opinion in Massachusetts v. EPA, 05-1120

• Roberts dissent

• Scalia dissent