BILLINGS, Mont. — Coal companies and their supporters scored a courtroom victory with a U.S. Supreme Court decision that said the Obama administration failed to take potential costs into account when it decided to regulate toxic emissions from many power plants.

But officials from New England states downwind of coal plants expressed disappointment, and the industry’s legal triumph comes with a major asterisk: The disputed regulation will remain in force while a lower court reconsiders the issue, according to federal officials and outside observers.

That means plants across the U.S. that burn coal and oil to produce electricity remain obligated under an April 2016 deadline to cut emissions of mercury and other toxic pollutants.

In a 5-4 ruling, the majority of justices said Monday the cost analysis should have been done earlier.