Rather than seeking money or punishment for the defendants, they seek what everyone should agree is the polluters’ responsibility: abatement of their huge, harmful part in causing climate change. The purpose is not to solve global warming or usurp the government’s role in doing so. It is, rightly, to get major utilities to curb their greenhouse-gas emissions before the government acts.

Because there is no federal regulation of this problem in force, it is fortunate that there is a line of Supreme Court precedents back to 1901 on which the plaintiffs can build their challenge. When this lawsuit began seven years ago, one of the defendants’ main defenses was that, because the Clean Air Act and other laws “address” carbon dioxide emissions, Congress has “legislated on the subject” and pre-empted the suit. The pre-emption claim was spurious when they made it and remains spurious now.

Seven years ago, neither Congress nor the Bush administration showed interest in pushing comprehensive laws or rules to curb these gases. Since then, the Environmental Protection Agency has found that greenhouse gases endanger public health as “the primary driver” of climate change and has regulated vehicle emissions.

But the electric power industry is working to scuttle this regulation, with the help of the Republican-controlled House. In court, the industry pushes for letting the E.P.A. regulate. On Capitol Hill, it tries to torpedo that authority.

For the United States Court of Appeals for the Second Circuit, two Bush appointees (one by the father, the other by the son) held that the prospect of regulation by the federal government is not enough to make this lawsuit go away. What the judges noted remains incontestable today: “E.P.A. does not currently regulate carbon dioxide” by requiring “control of such emissions” from existing power plants.

The judges reviewed five other major statutes that directly address the issue of climate change, beginning with the National Climate Program Act of 1978 a generation ago and running through the Energy Policy Act of 2005 passed while this lawsuit was under way.

They use italics to devastating effect, noting that these laws call for assessments, data collection, forecasts, improvements in understanding and all manner of other ground-laying efforts, but not one concrete action “to regulate greenhouse gas emissions in any real way.”

Yet the failure of the federal government to act, which has gone on for many years, doesn’t mean the plaintiffs must wait until it does. As the Second Circuit writes, they “may seek their remedies under the federal common law,” including made by justices. The Supreme Court has upheld a lawsuit preventing the discharge of sewage that made the Mississippi River unfit. It has upheld limits of noxious emissions of sulfur from copper foundries in Tennessee that were destroying Georgia forests. There are other clear-cut precedents.

The appellate court’s opinion closes by paraphrasing a Supreme Court opinion from almost 40 years ago. New federal regulation may pre-empt the federal common law of nuisance, but, until then, federal courts are empowered to address the public nuisance caused by major, undisputed and destructive sources of greenhouse gases.