High Court Hears Global Warming Case

On Nov. 29, the Supreme Court will hear oral arguments in the first case on global warming ever to come before the justices. In Massachusetts v. EPA, the main issue is whether the Environmental Protection Agency has authority under the Clean Air Act to regulate greenhouse gases—carbon dioxide chief among them—from new cars and trucks.

The case has been brought by 12 states, including Massachusetts, California, and New York. Lawyers from the 12 states will argue that the Clean Air Act requires EPA to impose limits on carbon dioxide and other greenhouse gases emitted by new vehicles. The act says EPA "shall" set standards for any air pollutant that "may reasonably be anticipated to endanger public health or welfare." The law also states that welfare includes effects on climate and weather.

The Bush Administration, however, will argue that EPA lacks the power to limit greenhouse gases. In addition, it will contend that the states do not have standing to sue EPA because they cannot show that they will be specifically harmed by the agency's failure to regulate greenhouse gases. Auto industry lawyers will argue that the nation's global warming policy should be decided by Congress and the President, not the courts.

The ruling will affect existing or future laws and regulations in the 12 suing states, which want to limit CO₂ emissions from new cars and trucks in the absence of EPA action. What's more, if the court decides that greenhouse gases from new cars and trucks can be regulated under the Clean Air Act, it opens the door for other states to follow suit and begin regulating those emissions.

The authority-to-regulate issue involves three separate but related questions: Can states and environmental groups sue the federal government to compel it to take action on climate change? Are greenhouse gases within the jurisdiction of the Clean Air Act? And if the Court answers these two questions affirmatively, does EPA have a duty to regulate greenhouse gases from motor vehicles?

A decision is expected in July 2007.