The smoke stacks at American Electric Power's Mountaineer coal power plant in New Haven, W. Va.
The smoke stacks at American Electric Power's Mountaineer coal power plant in New Haven, W. Va. - 
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Kai Ryssdal: As happens every year when the court's term winds down in mid-June, it's handing down rulings about as fast as they can be printed. Some of the country's biggest electric power companies got a win today. The justices unanimously rejected a lawsuit that would let states sue utilities over global warming emissions.

Sarah Gardner reports now from the Marketplace Sustainability Desk.

Sarah Gardner: This suit pitted half a dozen states, New York City, and some land trusts against some of the biggest coal-burning utilities in the country. Plaintiffs wanted the right to sue those utilities for greenhouse gas emissions. They argued those emissions were a federal nuisance, so federal judges could order power plants to cut them.

But the court didn't buy it, says Bruce Myers at the Environmental Law Institute.

Bruce Myers: Basically the court says, Congress has left it up to EPA under the Clean Air Act to regulate CO2 emissions.

But it's unclear how rigorously the EPA will restrict those emissions. Bill Fang is an attorney with a utility trade group. He fully expects the EPA to regulate greenhouse gases, despite congressional and corporate opposition. But he says groups like his are lobbying the EPA for more "flexibility." And intense lobbying has already gotten the EPA to delay draft rules on power plant emissions. State regulators, Fang says, are applying pressure as well.

Bill Fang: I think they're very concerned about the effects of further regulations in terms of cost impacts on customers.

Today's Supreme Court ruling did leave one important question unanswered -- whether state courts can decide such cases. Corporate attorneys argue these kind of climate change nuisance suits are "equally flawed" under state laws.

I'm Sarah Gardner for Marketplace.

Follow Sarah Gardner at @RadioGardner