By John Kruzel and Andrew Chung
WASHINGTON, Oct 5 (Reuters) - US Supreme Court justices wrestled with a bid by oil companies ExxonMobil and Suncor Energy to thwart a lawsuit by officials in Boulder, Colorado, seeking monetary damages for harms caused by climate change, as they opened their new nine-month term on Monday.
US-based Exxon and Canada-based Suncor appealed after the Colorado Supreme Court let Boulder's lawsuit accusing them of state law violations proceed.
"This case involves an unprecedented
effort to use state law to regulate global conduct," Kannon Shanmugam, a lawyer for the oil companies, told the justices.
Boulder is suing the oil companies under Colorado law, Shanmugam added, "on the theory that their global conduct increased the global use of fossil fuels, which led to an increase in global greenhouse gas emissions, which contributed to global climate change, which resulted in global harms."
"Our constitutional system does not permit state law to be used in that manner. The Constitution bars the application of state law to certain inherently federal areas," Shanmugam said.
"Because of the ambient nature of air and water and the conflicting rights of states, this court has held for over a century that federal law governs interstate pollution claims. That principle applies with even greater force to claims involving global climate change," Shanmugam said.
Boulder's city and county governments have accused Exxon and Suncor of helping drive climate change and misleading the public about the risks of fossil fuels. Boulder aims to hold the companies liable for past and future costs associated with climate change such as infrastructure repairs, environmental damage, emergency management and harms to public health.
President Donald Trump's administration has backed Exxon and Suncor, arguing that the federal government's authority to regulate air pollution precludes Boulder's claims.
"Interstate air pollution is an inherently federal area," said Sarah Harris, a Justice Department lawyer representing the Trump administration, and Congress has not authorized the Boulder suit under a key provision of the Clean Air Act, the landmark federal anti-pollution law.
"Second, this suit egregiously exceeds constitutional limits on state authority," Harris told the justices.
Conservative Chief Justice John Roberts pressed Shanmugam and Harris on their contention that state lawsuits are barred when such litigation has been allowed in similar contexts.
"I guess I'm not quite sure what makes this situation different from all those other ones where we've allowed (it)," Roberts told Harris.
The top US judicial body opened its new term on the first Monday in October, as is its custom. It also has major cases involving Trump's hardline immigration policies and state-level bans on assault-style rifles, among others, lined up for the term. Before the arguments, the court turned away some appeals including in cases involving bids by real estate platform Zillow Group and Nexstar Media Group to avoid lawsuits.
'SORT OF PREMATURE'
The burning of fossil fuels releases greenhouse gases including carbon dioxide into the atmosphere, trapping heat and raising average global temperatures over time.
Nearly 60 state and local governments have brought similar suits seeking billions of dollars from fossil fuel companies, with more continuing to be filed, Exxon and Suncor told the justices. A ruling by the Supreme Court siding with the companies could lead to many of those cases being dismissed.
Liberal Ketanji Brown Jackson said some of the questions asked by her colleagues during the arguments "make me think that we're really early in this case" and "that this is sort of premature from the standpoint of this court exercising its jurisdiction."
"I understand that you have several other federal issues that you have raised that are still pending in the state court. So why shouldn't we wait and hear all of these claims once the state courts are done with their federal considerations?" Jackson asked Shanmugam.
"I would submit," Shanmugam replied, "that given the extraordinary magnitude of these cases, where in each of these cases plaintiffs are seeking billions of dollars of damages, that we need an answer to this question sooner rather than later."
"And just as a matter of judicial administration, given the number of these cases that are in courts around the country, that the time is really now for this court to resolve these issues," Shanmugam said.
Monday's arguments marked the latest example of energy-sector companies asking the justices to block climate-related liability or limit federal environmental regulation.
Backers of the oil companies argue that if Boulder's most far-reaching claims are allowed to proceed, it could give states sweeping power over conduct occurring far outside their borders.
Energy companies and trade groups, along with states allied with them, have built a largely winning record before the justices over the past two decades in cases involving climate liability and the reach of federal environmental regulation.
The court has a 6-3 conservative majority. Conservative Justice Samuel Alito has recused himself from participating in the case, meaning the ruling will be made by eight justices and not nine. Alito owns stock in several oil and gas companies but not Exxon or Suncor, according to his financial disclosure forms.
The Supreme Court's decision is expected by the end of June.
(Reporting by John Kruzel; Editing by Will Dunham)
