As globe warms, can states force the EPA to act?

Arctic sea ice is melting. Glaciers are in retreat. Sea levels are rising. So what is the Environmental Protection Agency doing about it?

That's what a group of state officials and environmentalists want to know.

Seven years ago, they asked the EPA to get involved – to take an initial step in response to scientific evidence that suggests greenhouse gases are causing global warming.

The agency refused, saying there were too many unresolved questions about the causes and effects of global warming. The state officials took their case to court, charging that the Clean Air Act requires the EPA to take immediate action.

On Wednesday, the dispute arrives at the US Supreme Court, where the justices must decide whether the EPA is required to take action or whether the agency retains the discretion to decide for itself how best to respond to world-wide environmental threats.

The case will test the authority of special interest groups and state governments to sue federal agencies and force them to adopt certain regulatory policies that they favor. The case could also establish important legal precedents that might help or hinder state efforts to regulate greenhouses gases on their own in the absence of federal action.

On a broader level, the case raises questions about the role of the judiciary in resolving litigation over regulatory policy arguments. Should judges defer to controversial decisions made by administrative agencies on whether or when to pass regu-lations? Or should judges aggressively enforce what they see as the underlying purpose of statutes that govern agencies?

At issue in Massachusetts v. US Environmental Protection Agency is whether EPA officials acted properly when they declined to issue national regulations limiting the release of four greenhouse gases from new automobile models. The gases are carbon dioxide, methane, nitrous oxide, and hydrofluorocarbons.

EPA officials say the agency lacks the power to regulate greenhouse gases. The Clean Air Act authorizes the EPA to take action to reduce and control agents that cause "air pollution." But agency officials have concluded that greenhouse gases are not agents of air pollution. They say the Clean Air Act does not address global climate change.

As a fallback position, EPA officials say that even if they do have authority to regulate greenhouse gases under the Clean Air Act they also have discretion under the act to decide when to initiate such measures. The officials have said there was scientific uncertainty about global warming and that they wanted to wait for more research and additional action by Congress before crafting an appropriate response.

Massachusetts along with 11 other states, three cities, a US territory, and numerous environmental groups are urging the Supreme Court to order the EPA to faithfully enforce the law as passed by Congress.

"A straightforward reading of the language of the Clean Air Act shows that carbon dioxide and other air pollutants associated with climate change are 'air pollutants' potentially subject to regulation [under the Clean Air Act]," writes Massachusetts Assistant Attorney General James Milkey, in his brief. "When Congress has spoken as plainly as it has here, an administrative agency is bound to obey that legislative command."

In his brief, US Solicitor General Paul Clement defends the EPA's earlier legal positions. He also argues that Massachusetts lacks the legal standing to bring the lawsuit in the first place. Mr. Clement says Massachusetts officials are unable to draw a direct link between harm to the state and the EPA's decision not to pass the requested regulations.

Massachusetts and other petitioners in the case complain of "profound harms" caused by climate change including the inundation of coastal property, damage to seaside facilities, and additional emergency response costs from more frequent and intense storms. Clement argues that the state's generalized concerns are not enough to demonstrate that such cataclysmic harms are a direct result of the EPA's decision not to regulate.

The specific request was for the EPA to regulate greenhouse-gas emissions from new cars. Such emissions make up only a fraction of greenhouse gases released worldwide.

Clement says that 80 percent of all greenhouse gases are from countries other than the US and that, of US emissions, 70 percent are from nontransportation sources. The solicitor general adds that of the remaining 30 percent, the requested regulation would only affect new vehicles models – leaving the vast majority of emissions in the US and throughout the world not covered by the new regulations.

In effect, Clement says, the threat of global warming is an international threat that requires an international solution. Since the EPA acting alone cannot solve the problem, lawyers from Massachusetts don't have legal standing to try to hold the EPA responsible for a problem it can't solve without international cooperation.

Mr. Milkey says the primary concern of Congress in the Clean Air Act was for the agency to determine whether certain pollutants can reasonably be anticipated to endanger public health or welfare. Where they pose such a threat, Milkey says, the agency must act to protect the public.