The utilities and the Obama administration want the Environmental Protection Agency (EPA) to enforce laws against global warming. But the states contend the EPA is not acting to limit carbon-dioxide emissions that lead to global warming.

She says the risk for businesses, insurers and ultimately consumers “is the potential for environmental regulation to be created on a case-by-case basis through nuisance suits.”

“This could lead to inconsistent rulings and requirements across the country—and virtually any business that allegedly contributed to climate change could become the target of a lawsuit,” Spragins says.

She adds that these questions are “political in nature, and Congress and the [EPA]—rather than the courts—are the appropriate governing bodies to determine these issues.”

“We urged the court to take the position that environmental public-nuisance suits are viable only if the source of the pollution is limited to a well-defined geographical locality and the alleged damage can be traced or directly linked to the defendants' actions,” Spragins says. “Since climate change is a global phenomenon, it is impossible to determine the source of the pollution or prove specific damages due to the actions of the defendants.”

During the oral arguments, a representative of the Obama administration joined with power-company lawyers in calling the scope of the lawsuit unprecedented, involving national and international issues outside the power of the courts.

The utilities are American Electric Power Co. Inc., Southern Co., Xcel Energy Inc. and Cinergy Corp., which Duke Energy Corp. acquired in 2006. The Tennessee Valley Authority (TVA), which joined the lawsuit, wants it dismissed.