WASHINGTON — The Obama administration's drive to regulate global-warming gases won a surprising victory in the Supreme Court on Monday with the support of two conservative justices.
Chief Justice John Roberts and Justice Antonin Scalia joined the court's moderates and liberals in a 7-2 vote to uphold most of an Environmental Protection Agency rule that requires new or rebuilt factories and power plants to use the "best available technology" to limit their emissions of carbon dioxide and other greenhouse gases.
Because these "major polluters" are already required to obtain clean-air permits from the government, the EPA is justified in adding greenhouse gases to the list of restricted pollutants, Scalia wrote for the court.
It was the third time the high court has upheld the use of the 1970s-era Clean Air Act to combat challenges posed by 21st century climate change. Environmental advocates were elated, saying the decision showed that a strong majority of justices support the EPA's authority to regulate greenhouse gases.
"The EPA's foundational authority under the Clean Air Act to protect Americans' health from the clear and present danger of climate pollution is rock solid," said Vickie Patton, a lawyer for the Environmental Defense Fund.
Patton said the ruling is a "big win" not just for the agency's efforts to regulate new power plants, but also for the Obama administration's sweeping climate change rules aimed at the nation's existing power plants. The proposed rules, announced this month, call for an average 30 percent cut in greenhouse gases nationwide by 2030.
Monday's ruling also served as a legal vindication of sorts for President Barack Obama, who has sought to use his executive and regulatory powers to fight global warming because he says Congress has been unwilling or unable to act on the issue.
The Supreme Court opened the door for a national drive against global warming in 2007 when it ruled for the first time that greenhouse gases could be restricted as "air pollutants" under the Clean Air Act. Until then, the law had been applied to conventional pollutants such as ozone, lead or carbon monoxide. That 5-4 ruling arose when Democratic-led states — including Massachusetts, California and Illinois — sued to challenge what they called the Bush administration's inaction.
Later, when Obama took office, the court expanded on that decision, ruling that the EPA could restrict greenhouse gases from power plants and refusing to block the agency's carbon emissions standards for cars and trucks.
Even so, industry advocates hoped a conservative-leaning Supreme Court would veto the more expansive liberal regulations coming from Obama's agencies, noting that Roberts and Scalia had disagreed with the 2007 ruling that labeled carbon dioxide as a dangerous air pollutant. But in Monday's decision, both justices accepted that ruling as law.
Justices Samuel Alito and Clarence Thomas disagreed with the majority opinion.