THE DEMOCRATS’ global warming bill died in the Senate last year. The new Republican majority in the House wants to gut carbon regulations at the Environmental Protection Agency. President Obama is reluctant even to discuss global warming publicly. So some environmentalists believe that a case being argued before the Supreme Court Tuesday represents the last, best hope to reduce greenhouse emissions.

This is not where environmentalists had hoped to be when the case, American Electric Power v. Connecticut, was launched in 2004. A group of states and New York City sued several electric companies that year, claiming that the greenhouse emissions from their power plants are a “public nuisance” because they contribute to global warming. Climate change directly harms California’s snowpack, New York’s sea level, shipping in the Great Lakes and so forth, the states argued, and so they turned to an element of common law, non-statutory legal norms imported from England centuries ago that allow for nuisance suits when one party’s activity harms others.

A U.S. District Court judge curtly threw out the states’ case, saying that plaintiffs were asking the judicial branch to settle an inherently political question. The states persuaded the U.S. Court of Appeals for the 2nd Circuit to reverse the district court’s ruling, arguing that, under ancient and recent precedent, courts have settled nuisance claims similar to those in AEP v. Connecticut.

The 2nd Circuit’s ruling hinged in part on the argument that the political branches had failed to devise a clear policy addressing global warming, a policy that might have “displaced” common law. Now the executive branch has a policy — no matter how underwhelming — on climate change: The Obama administration, opposing the states in this case, persuasively argues that carbon emission regulations on track in the Environmental Protection Agency address the “nuisance” identified in the states’ lawsuit.

There’s a good reason that common law is displaced when the political branches speak. It’s not the place of unelected judges to determine how to distribute the costs of addressing climate change across the economy. In addition, a series of suits against individual polluters or groups of emitters is likely to result in an inefficient patchwork of judicial remedies, varying in scope and expense. Consistently applied regulation at the EPA is far better.

It’s reasonable to worry that the political branches may ultimately fail to enforce even the EPA’s modest greenhouse gas policies; many Republicans are eager to defund the agency’s efforts. If that happens, the plaintiffs will have a better case than they do now. But no one should wish to see America’s climate change policy made in court.