Liberal and conservative U.S. Supreme Court justices on Tuesday skeptically met arguments that power plant owners emitting global warming–causing greenhouse gases (GHGs) can be sued for damages. Justices questioned the court’s jurisdiction to decide on emissions standards, the vast scope of the case, and factors to assess the best available technologies to curb GHG emissions.

The high court heard oral arguments (transcript) in American Electic Power Co. v. Connecticut, a lawsuit brought against American Electric Power (AEP), Southern Co., Duke Energy, Xcel Energy, and the Tennessee Valley Authority (TVA) by eight states, the City of New York, and three private land trusts. The states had sought an injunction requiring emission-reductions from fossil fuel–fired facilities owned by the defendants, citing a variety of climate change–related injuries, including that carbon dioxide emitted by the power plants constituted a “public nuisance.”

The U.S. District Court of the Southern District of New York had in 2005 dismissed the case, saying claims presented a “political question,” which the court did not have the jurisdiction to decide. But in September 2009, a two-judge panel of the U.S. Court of Appeals for the Second Circuit reversed the district court’s decision in a 139-page opinion, rejecting the defendant’s claim that the litigation presented a “political question.”

The power companies—supported by the Obama administration, which filed a separate brief on behalf of the federally owned TVA—in August 2010 petitioned the U.S. Supreme Court to hear the case.

On Tuesday, Gen. Neal Kumar Katyal, acting solicitor general at the Department of Justice, representing the TVA said that the Supreme Court in its 222 years had never heard a case with so many “potential perpetrators and so many potential victims.” New York Solicitor General Barbara D. Underwood acknowledged the broad scope of the case, but asked that the court not block the suit until federal regulations from the Environmental Protection Agency (EPA) were in place.

Justice Elena Kagan also questioned the scope of the case, refuting Underwood’s argument that public nuisance pollution suit was like any other pollution suit. “All those other pollution suits that you’ve been talking about are much more localized affairs. One factory emitting discharge into one stream—they don’t involve these kinds of national/international policy issues … I mean, there’s a huge gap, a chasm between the precedents you have and this case, isn’t there?”

Justice Ruth Ginsburg, meanwhile, questioned the court’s jurisdiction in setting standards for emissions. “Asking a court to set standards for emissions sounds like the kind of thing that EPA does,” she said. “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.”

An equally prevalent question was which factors would go into the cost-benefit analysis needed to decide what level of emissions were reasonable in light of the threat of global warming, Chief Justice John Roberts said. Underwood replied that the best available technology and the cost of that technology would be significant factors.

“Obviously, the greatest benefit to reduce global warming would be, of course, to shut down the power plants, right,” Chief Justice Roberts said. He added: “I mean, across the economy, the whole problem of dealing with global warming is that there are costs and benefits on both sides, and you have to determine how much you want to readjust the world economy to address global warming. And I think that’s a pretty big burden to post—to impose on a district court judge.”

Underwood responded that suits presented to a district court judge to decide would need to prove that the defendants have practical, feasible, and economically viable options for reducing carbon dioxide emissions without “significantly increasing the cost of electricity to their customers.” This could include changing fuels and improving efficiency.

The Supreme Court could issue a decision on the case as early as this summer.

Sources: POWERnews, U.S. Supreme Court