The new proposal directs the E.P.A. to do just that. Should that plan ultimately go into effect, the cost to curb mercury would be calculated in a way that shows the costs outweighing the health benefits.
With the legal justification for the regulation thus weakened, experts said, the rule could more easily be overturned if challenged in court. Moreover, it could make it more difficult for future regulations to go into effect.
“There is a likelihood that this rule-making will be the administration’s flagship effort to permanently change the way the federal government considers health benefits,” said Janet McCabe, who ran the E.P.A.’s air office under Mr. Obama.
She said an overhaul of the mercury rule could result in utilities opting to no longer run pollution controls, despite having already installed them, because costs that are not federally mandated can no longer be passed on to ratepayers. “If that’s the case, we will see higher emissions of mercury, arsenic, acid gases and the particulate matters that are also captured along with those pollution controls,” Ms. McCabe said.
Mr. Wheeler, in a recent interview, dismissed the idea that utilities, having spent billions of dollars on pollution controls, would stop using them. “It’s not like people are going to start taking off their equipment and start putting mercury into the atmosphere,” he said.
He described the E.P.A.’s action as simply a response to a Supreme Court’s 2015 decision that said the Obama administration had failed to properly consider economic costs when they imposed the mercury rule and ordered a new cost-benefit analysis. The Obama administration complied and the rule was reinstated, but the coal industry again challenged the rule.
When the Trump administration came into office, the agency said it would no longer defend the Obama administration’s cost-benefit finding and would seek to rework the rule entirely.
Mr. Wheeler described the E.P.A.’s plan to reopen the mercury rule as an answer to the court and said he was not concerned by either the utility industry’s disinterest in seeing the rule reworked or the views of his former client, Mr. Murray. “We don’t answer to the utility industry,” he said. “We don’t answer to the coal industry. We answer to Congress and the courts, and the Supreme Court told us we didn’t get it right. We have to redo it. I’m going to follow the law, and I’m going to follow the Supreme Court.”
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