Washington (CNN) -- The Supreme Court on Monday unanimously tossed out a massive lawsuit brought by several states against private power companies whose greenhouse-gas emissions are accused of presenting a "public nuisance."
The 8-0 ruling could have enormous implications on competing government efforts to control what many have claimed is major factor in global warming.
At issue was whether the federal courts can intervene and unilaterally establish targeted pollution emission levels, or whether federal government regulators under the Environmental Protection Agency should have the final say. The justices were clearly concerned that the scope of the problem and the possible solutions would be too much for courts to tackle.
"We have before us, to put it plainly, a 'who decides' question," wrote Justice Ruth Bader Ginsburg. "The EPA is currently engaged in a rulemaking to decide whether the agency should set limits on emissions from domestic power plants. The Clean Air Act, in our judgment, leaves no room for a parallel track" giving judges power to decide a binding regulatory cause of action.
The energy companies, backed by the Obama administration, had agreed, saying federal judges should not be setting environmental policy, especially on such a complex issue as clean air standards.
The EPA claimed 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, had 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 high court's decision allows environmental groups to continue to press their climate change claims, but in a different judicial forum.
The carbon dioxide 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, and 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 than the judicial branch to handle what they consider a "political" issue on public policy.
The current appeal offered 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 only decided whether the lawsuit could proceed to trial.
The high court hinged its decision on an earlier 2007 ruling in which the justices said the federal government had the authority and responsibility to regulate carbon dioxide emissions from cars and factories. States sued after Bush administration officials argued CO2 is not a "pollutant" under EPA standards, and they alone had discretion to decide regulation and enforcement.
The ruling in that earlier case gave states "standing" to sue the EPA over its greenhouse gas enforcement.
Justice Sonia Sotomayor did not participate in the case. She had recused because of her participation when the case was argued in the lower courts.
Future litigation in this dispute 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).