Washington (CNN) -- The Supreme Court appeared reluctant Tuesday to allow a massive lawsuit by several states to proceed against private power companies whose greenhouse-gas emissions are accused of presenting a "public nuisance."
The environmental policy issue could have enormous implications on competing government efforts to control what many have claimed is major factor in global warming.
At issue is whether the federal courts can intervene and unilaterally establish targeted pollution emission levels, or whether federal government regulators should have the final say. Several justices worried that the scope of the problem and possible solutions might be too much for courts to tackle.
"The whole problem of dealing with global warming is that there are costs and benefits on both sides," said Chief Justice John Roberts, "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 impose on a district court judge."
"Do you think that you have a federal common law cause of action against anybody in the world?" asked Justice Elena Kagan of the states' attorney. "Is there something that you think limits it to large emissions producers?"
The energy companies, backed by the Obama administration, say federal judges should not be setting environmental policy, especially on such a complex issue as clean air standards. The Environmental Protection Agency claims it has been actively working to beef up rules to control carbon dioxide emissions that cross over state lines from individual power plants.
But several states, backed by land trusts and environmental groups, have sued five private utilities and the federal Tennessee Valley Authority, saying U.S. authorities have not been aggressive enough in curbing emissions, which they say has led to increased smog, soaring temperatures and loss of forests and cropland.
The CO2 produced from the burning of coal, petroleum, and other fossil fuels has contributed to global warming, in the estimation of most of the scientific community. The plaintiffs allege the utilities being sued have together been spewing 650 million tons of CO2 each year, about 10 percent of the annual U.S. output. They say feasible, cost-effective alternatives have been ignored.
The companies have countered that the proposed changes could make electricity rates quadruple, devastating the economy and families. They also worry that losing the case could lead to a flood of lawsuits against small companies, individuals using gas-powered lawn mowers, even dairy farmers with cows that naturally emit methane gas.
Supported by a range of business interests, utilities say the two other government branches are better equipped to handle what they consider a "political" issue on public policy.
The current appeal offers the high court another chance to debate the larger implications of separation of powers, and the roles the judicial, legislative and executive branches should play.
The justices for now will only be deciding whether the lawsuit can proceed to trial. A ruling can be expected by early summer.
In the 80-minute arguments, Peter Keisler, representing the electricity-generating firms, said it is wrong to force the courts "to perform a legislative and regulatory function."
Acting Solicitor General Neal Katyal, speaking for the administration, added, "This court has never had a case involving this scale and scope."
The separation of powers argument hinges on whether courts in this case should be drafting so-called "common"-- or judge-made -- law, or is current legislation and regulation enough to "displace" judicial authority over the pending lawsuit.
On the other side, New York's solicitor general Barbara Underwood urged the justices to 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."
That brought some concern from both the left and the right over just who could sue over polluted air, and who would ultimately decide how to tackle the problem.
Justice Ruth Bader Ginsburg said, "Congress set up the EPA to promulgate standards for emissions, and now the relief you're seeking seems to me to set up a district court judge, who does not have the resources, the expertise, as a kind of 'Super EPA.'"
Giving judges the power to establish binding, "reasonable" emission standards troubled Justice Samuel Alito, who worried about the practical effects from making "difficult trade-offs."
"If a certain reduction in greenhouse gas emissions is ordered, that will have this effect, it will increase the cost of electricity by a certain amount," he hypothesized. "It will result in the loss of a certain number of jobs, it will mean that consumers will have less money to spend on other things. Some people will not be able to have air conditioning in the summer. That will have health effects. What standard does the district judge have to decide those?"
Justice Antonin Scalia suggested everyone could be made to blame for the problem, including non-humans.
"You're lumping them all together," he said of power companies big and small. "Suppose you lump together all the cows in the country" emitting methane gas. "Would that allow you to sue all those farmers? I mean, don't you have to do it defendant by defendant? Cow by cow, or at least farm by farm?" He later wondered whether every person who exhales C02 through normal breathing should also be held accountable.
What the Supreme Court does in the current dispute may hinge on a 2007 ruling in which the justices said the federal government has the authority and responsibility to regulate carbon dioxide emissions from cars and factories. States sued after Bush administration officials argued CO2 was not a "pollutant" under EPA standards, and they alone had discretion to decide regulation and enforcement.
The ruling in that case gave states "standing" to sue the EPA over its greenhouse gas enforcement.
Complicating matters this time is that Justice Sonia Sotomayor is not participating in the case. She has recused because of her participation when the case was litigated in the lower courts. A potential 4-4 tie would not establish guiding precedent, but would allow the suit to proceed in lower federal courts. The case also could become moot if Congress and the agency put in place proposed emission regulations that have been in the works for several years.
The case is American Electric Power Co. v. Connecticut (10-174).