The U.S. Supreme Court heard oral arguments November 29 on the U.S. Environmental Protection Agency's (EPA) authority under the Clean Air Act to regulate carbon dioxide and other greenhouse gases (GHG) in new cars and trucks. The case, Massachusetts v. EPA, marked the first time the Court has heard arguments related to climate change. The Justices appeared most interested in whether the petitioners had standing to bring the case, and the Court spent little time on regulatory and environmental questions.

According to a BNA story and supported by the transcript of the oral argument, most of the questions from Justices Antonin Scalia, Anthony Kennedy, Samuel Alito and Chief Justice John Roberts focused on whether the petitioners suffered real harm from climate change, the standard for achieving legal standing. James R. Milkey, assistant attorney general for Massachusetts, argued the case on behalf of several states, environmental groups and three cities. In his responses to the standing questions, Milkey noted that Massachusetts alone is likely to lose more than 200 miles of coast as climate change occurs.

Deputy Solicitor General Gregory C. Garre, arguing on behalf of the EPA and the auto industry, said the administrative decision not to regulate GHG from new vehicles was an appropriate exercise of agency discretion. Garre also argued that the science of climate change is too uncertain for development of regulatory standards. The Bush administration has consistently argued this position, coupled with its concerns about the economic impact of regulating GHG.

Roberts and Alito noted that since auto emissions make up only about six percent of carbon dioxide emissions, the effect of federal regulations would be relatively small. This ignores the potential impact that a regulatory regime for carbon dioxide would have on emissions from other sources. Utilities, refineries, manufacturers and automakers would potentially be affected by EPA's ability to regulate GHG. Such regulation would also enhance the potential for development of cleaner technologies, green buildings and solar power. Industry groups are split over this issue; many industries moving toward a non-carbon future support the regulation of GHG.

Four Justices, David Souter, Ruth Bader Ginsberg, Stephen Breyer and John Paul Stevens, appeared more skeptical of the government's position. Souter argued that even small improvements in the amount of harmful emissions would lead to real benefits. Stevens noted that, according to EPA scientists involved in the decision, the agency omitted information from its administrative response that would have supported existing scientific information on climate change.

The Court's decision is expected in the spring, with Kennedy being the all-important swing vote. If the petitioners win, the case will be sent back to the EPA for reconsideration of its decision on whether to regulate GHG; if the Court decides in EPA's favor, the decision not to regulate stands.

The case stems from a 2003 decision in which the EPA claimed it did not have the authority to regulate GHG emissions from new vehicles under Section 202 of the Clean Air Act. That decision was appealed in 2005 to the U.S. Court of Appeals for the DC Circuit, which issued a split opinion on the matter.

The outcome has significance for efforts at the state and regional levels to regulate GHG. In the Northeast, the Regional Greenhouse Gas Initiative (RGGI) is a cooperative effort to regulate carbon dioxide in states from Maine to Delaware. California also has a GHG initiative that is currently being challenged by the auto industry and may be impacted by the Court's decision in Massachusetts v. EPA.