The Supreme Court's conservative justices questioned the high cost of a new Obama administration environmental regulation Wednesday, raising the possibility they could block the strict emissions rule for coal-fired power plants.
Chief Justice John Roberts said it "raises a red flag" when the Environmental Protection Agency says the rule would cost about $9.6 billion a year, but save only about $6 million a year by removing toxic mercury from the air.
"Your position is you don't need to consider costs," a skeptical Justice Anthony Kennedy told a lawyer defending the new rule.
The justices sounded closely split on whether to uphold or reject the EPA's "mercury and air toxics" rule. It was adopted in 2012 and was due to take full effect this year.
Lawyers for the power industry and the state of Michigan urged the high court to block the rule because the EPA didn't conduct a cost-benefit analysis.
Justice Antonin Scalia called the failure to consider costs "silly" and not the normal way to regulate.
But the court's liberal justices defended the EPA, noting that neither the law itself nor past decisions told regulators they should weigh the costs against the harm to the public's health.
U.S. Solicitor Gen. Donald Verrilli said the EPA was told by Congress to protect the public against toxic pollutants like mercury and arsenic. The law "doesn't mention costs," he said.
But even liberal Justice Stephen Breyer voiced skepticism at one point. "Nine billion dollars is a lot of money," he said. It "begins to look irrational" if costs are not considered.