The Supreme Court has ruled against federal regulators' attempt to limit power plant emissions of mercury and other hazardous air pollutants.
The challenge was brought by industry groups and 21 Republican-led states. When the case was argued in March, the court's conservative justices seemed divided, with some questioning whether EPA was required to take costs into account or whether the Clean Air Act demands that health risks are the only consideration the EPA should consider in regulating hazardous air pollutants from power plants.
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The rules began to take effect in April, but the court said in a 5-4 vote Monday that the Environmental Protection Agency failed to take their cost into account when the agency first decided to regulate the toxic emissions from coal- and oil-fired plants.
Justice Antonin Scalia, who wrote the opinion, also said from the bench, "It is not rational, never mind 'appropriate,' to impose billions of dollars in economic costs in return for a few dollars in health or environmental benefits."
The case now goes back to lower courts for the EPA to decide how to account for costs. The EPA did factor in costs at a later stage when it wrote standards that were expected to reduce the toxic emissions by 90 percent. EPA had estimated the cost of the rule at $9.6 billion each year.