A detail of the West Facade of the U.S. Supreme Court is seen in Washington, Monday, March 7, 2011. (J. Scott Applewhite/AP)

Supreme Court justices across the ideological spectrum signaled Tuesday that they might halt a huge global-warming lawsuit in which states are asking the federal courts to restrict polluting power plants outside their borders.

“Asking a court to set standards for emissions sounds like the kind of thing that EPA does,” said Justice Ruth Bader Ginsburg, referring to the Environmental Protection Agency. “I mean, Congress set up the EPA to promulgate standards for emissions, and . . . the relief you’re seeking seems to me to set up a district judge, who does not have the resources, the expertise, as a kind of ‘super-EPA.’ ”

New York Solicitor General Barbara D. Underwood, arguing on behalf of six states, New York City and three land preservation groups, faced similar skepticism from the rest of the court. In addition, she had to contend with spirited opposition from the Obama administration, which said allowing the suit to move forward would be an epic mistake.

“In the 222 years that this court has been sitting, it has never heard a case with so many potential perpetrators and so many potential victims,” said Acting Solicitor General Neal Katyal. “The very name of the alleged nuisance — ‘global warming’ — itself tells you much of what you need to know. There are billions of emitters of greenhouse gasses on the planet and billions of potential victims as well.”

Washington lawyer Peter D. Keisler, representing the power plants, told the court that balancing the need for providing energy with the environmental costs of global warming “is among the most complex, multifaceted, and consequential of any policy issue now before the country” and is not suited for federal judges.

The court in 2007 said that carbon dioxide and other greenhouse gases are air pollutants that can be regulated under the Clean Air Act by the EPA. It said the agency could regulate auto emissions, and the effort now is underway to address existing power plants.

The problem, Underwood told the court, is that Congress and the executive branch have been slow and reluctant.

Despite recent efforts of the Obama administration and its EPA to move on setting restrictions, some congressional Republicans want to deny the agency the power to deal with greenhouse gasses associated with climate change.

“It could be a long time before EPA actually arrives at a judgment,” Underwood told the court. “A lot can happen to delay or derail the fulfillment of a promise.”

In the meantime, she said, the court should “keep the federal courts open to states exercising their historic power to protect their land and their citizens from air pollution emitted in other states.”

Eight states initially banded together to sue: California, Connecticut, Iowa, New Jersey, New York, Rhode Island, Vermont and Wisconsin. New Jersey and Wisconsin have since withdrawn. States may regulate utilities within their borders, but need to go to federal court about pollution that crosses state lines.

The states are suing older power plants in Ohio, North Carolina, Georgia and Minnesota, as well as the Tennessee Valley Authority. Underwood said collectively those plants produce 650 tons of carbon dioxide, about 10 percent of the country’s emissions.

Although the issue before the justices was whether the case could go to trial before a district judge, they continually strayed into questions about how a federal judge could go about deciding such a case.

Underwood said courts have been deciding such cases for years, including an early 20th-century case in which a Tennessee company was ordered to reduce sulfur emissions because it was harming trees in Georgia.

“But do you seriously argue this isn’t orders of magnitude more complicated than that case?” asked Justice Samuel A. Alito Jr. He provided a list of questions he thought a federal judge would have a particularly difficult time answering.

Justice Antonin Scalia wondered how a judge could order reductions by the specific plants that would make an impact on global warming, and questioned Underwood’s grouping of the utilities.

“You’re lumping them all together,” Scalia said. “Suppose you lump together all the cows in the country. Would that allow you to sue all those farmers? I mean, don’t you have to do it defendant by defendant?”

Justice Sonia Sotomayor did not participate in the case. She was on the panel of the U.S. Court of Appeals for the 2nd Circuit in New York, which heard the case. She was nominated and confirmed to the Supreme Court before the decision to allow the case to move forward was announced.

The case is American Electric Power Co. v. Connecticut .