* At issue: Should judges decide greenhouse gas curbs
* Ruling expected by end of June
* Most important environmental case since 2007
By Deborah Zabarenko and James Vicini
WASHINGTON (Reuters) - The Supreme Court
Tuesday questioned whether a global warming lawsuit against
five big power companies can proceed, with several justices
saying the U.S. Environmental Protection Agency, not federal
judges, should deal with the issue.
The high court justices sounded a skeptical note during
arguments when they asked whether complicated environmental
issues, such as how much greenhouse gas pollution is allowable
and how it should be curbed, should be left to federal judges.
The big environmental case stemmed from a 2004 lawsuit
claiming that five coal-burning utilities have created a public
nuisance by contributing to climate change. Its consequences,
such as rising seas, reduced crop yields and destruction of
some hardwood trees, would harm the states' citizens.
The lawsuit, now involving six states, seeks to have a
federal judge in New York order the utilities to cut their
carbon dioxide emissions.
Both liberal and conservative justices questioned whether
the lawsuit can go forward.
Justice Ruth Bader Ginsburg, one of the court's liberals,
took aim at the states' case, saying what they want is what the
Environmental Protection Agency is trying to do with its
proposed regulations of carbon emissions.
"How does a district judge decide what's reasonable and
effective?" conservative Justice Samuel Alito asked
rhetorically.
Another conservative, Chief Justice John Roberts, also
asked whether a district court judge could conduct the
cost-benefit analysis to determine what was reasonable to
reduce global warming: "I think that's a pretty big burden to
impose on a district court judge."
Liberal Justice Elena Kagan said the facts at issue in the
lawsuit usually were determined by an agency such as the EPA,
rather than the courts. "There is an administrative agency.
There is a Clean Air Act," she said.
EPA'S ROLE
Lawyers for the power companies, including an Obama
administration attorney representing the government-owned
Tennessee Valley Authority, said the scope of the lawsuit was
unprecedented in U.S. history, involving national and
international issues outside the power of the courts.
"In the 222 years that the court has been sitting, there
has never been a case with so many potential perpetrators and
so many potential victims," said Neal Katyal, the
administration's top courtroom lawyer.
The power companies -- American Electric Power Co Inc,
Southern Co, Xcel Energy Inc and Cinergy Corp, which Duke
Energy Corp acquired in 2006, along with TVA -- want the
lawsuit dismissed.
The states -- California, Connecticut, Iowa, New York,
Rhode Island and Vermont -- said their citizens have been
harmed by global warming and urged the top court to allow their
lawsuit to go forward.
It is the most sweeping climate change case to come before
the high court since its landmark 2007 ruling that authorized
the EPA to regulate greenhouse emissions if they endanger human
health.
In their comments on Tuesday, the justices said Congress
has given the federal environmental agency the authority to do
just that.
But even though the EPA has found officially that
greenhouse pollution poses a health hazard, it has not yet gone
forward to impose regulations on emissions, and Republicans in
Congress have sought to limit the agency's ability to do so.
Coal-fired power plants emit about twice as much carbon
dioxide -- which warms the Earth by trapping solar heat in the
atmosphere -- as natural gas-fired plants. Nuclear power plants
emit virtually no greenhouse gases.
The five power utilities account for 10 percent of U.S.
carbon dioxide emissions, said Barbara Underwood, who argued
the case for the states.
A ruling is expected by the end of June.
(Editing by Bill Trott)
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