WASHINGTON (AP) -- In a major anti-pollution ruling, the Supreme Court on Tuesday backed federally imposed limits on smokestack emissions that cross state lines and burden downwind areas with bad air from power plants they can't control.
The 6-2 ruling was an important victory for the Obama administration in controlling emissions from power plants in 27 Midwestern and Appalachian states that contribute to soot and smog along the East Coast.
It also capped a decades-long effort by the Environmental Protection Agency to ensure that states are good neighbors and don't contribute to pollution problems elsewhere. The rule upheld Tuesday was EPA's third attempt to solve the problem.
The rule, challenged by industry and upwind states, had been cast by foes as an attempt by the Obama administration to step on states' rights and to shut down aging coal-fired power plants. Opponents said the decision could embolden the agency to take the same tack later this year when it proposes rules to limit carbon pollution. EPA Administrator Gina McCarthy has said the agency will be flexible and work with states on the first-ever controls on power plants for the gases blamed for global warming.
On Tuesday, the court upheld a rule adopted by the EPA in 2011 that would force polluting states to reduce smokestack emissions that contaminate the air in downwind states. Power companies and several states sued to block the rule, and a federal appeals court in Washington agreed with them in 2012.
The Supreme Court reversed that decision. Writing for the majority, Justice Ruth Bader Ginsburg acknowledged the complexity of the problem before EPA.
"In crafting a solution to the problem of interstate air pollution, regulators must account for the vagaries of the wind," Ginsburg wrote.
The high court said the EPA, under the Clean Air Act, can implement federal plans in states that do not adequately control downwind pollution. But the court also ruled that the EPA can consider the cost of pollution controls and does not have to require states to reduce pollution by the precise amount they send to downwind states.
McCarthy called the court's ruling "a resounding victory for public health and a key component of EPA's efforts to make sure all Americans have clean air to breathe."
But Justice Antonin Scalia, in a vigorous dissent from the outcome, said, "Today's decision feeds the uncontrolled growth of the administrative state at the expense of government by the people." Reading part of his dissent from the bench, Scalia said the result "comes at the expense of endorsing, and thereby encouraging for the future, rogue administration of the law."
Justice Clarence Thomas joined Scalia in dissent. Justice Samuel Alito took no part in consideration of the case.
The new downwind pollution rule was triggered by a federal court throwing out a previous Bush administration regulation. The Bush-era rule has remained in effect while the courts have weighed challenges to the latest version, and EPA officials said the Bush rule would remain in place while they digested the Supreme Court's opinion.
The new rule would cost power plant operators $800 million annually, starting in 2014, according to EPA estimates. Some $1.6 billion per year has been spent to comply with the 2005 Bush rule.
The EPA says the investments would be far outweighed by the hundreds of billions of dollars in health care savings from cleaner air. The agency said the rule would prevent more than 30,000 premature deaths and hundreds of thousands of illnesses each year.
"The Supreme Court today laid to rest the well-worn issue of how to regulate air pollution that is transported hundreds of miles throughout the eastern U.S. and that makes it nearly impossible for states acting alone to protect the health and welfare of their citizens," said Bill Becker, the executive director of the National Association of Clean Air Agencies, which represents air pollution control agencies in 45 states and territories and 116 major metropolitan areas nationwide.
Texas led 14 states and industry groups in challenging the rule. Most downwind states support it.
States had argued, and the lower court had agreed, that they deserved a chance to figure out how much they were contributing to pollution in other states and how to reduce it before the EPA prescribed fixes. The lower court also faulted the EPA for requiring states to reduce pollution through a complex formula based on cost that did not exactly match how much downwind pollution a state was responsible for.
Agreeing with the EPA, Ginsburg wrote that the realities of interstate air pollution "are not so simple." She wrote, "Most upwind states contribute to pollution to multiple downwind states in varying amounts."