President Obama’s plan to fight global warming was on trial Monday. The U.S. Supreme Court heard oral arguments over whether the administration had the authority to require that industrial facilities get permits when they emit large amounts of greenhouse gases.

Thirteen states, industrial groups and utility companies have petitioned the Supreme Court to rule that the Environmental Protection Agency does not have the authority to regulate greenhouse gas emissions from these facilities. Such a ruling would imperil Obama’s plan to fight global warming, the lynchpin of which is to cut U.S. greenhouse gas emissions.

“This case marks an extremely critical point in clarifying just how far the Obama Administration can extend their regulatory overreach, including by rewriting the Clean Air Act to suit its needs,” said Louisiana Republican Sen. David Vitter in a statement.

“This Administration has led a far-left agenda driven crusade to circumvent Congress at every opportunity, and this case could permit an unprecedented power grab by expanding how far it can go to regulate greenhouse gases,” Vitter said. “Legislative attempts like ‘cap and trade’ have failed because the American public knows these regulations could strangle our economy, and the implications of this case could cripple the democratic process.”

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