A federal appeals court says government regulators can try to halt construction projects at power plants if they think the companies didn't properly calculate whether the changes would increase air pollution.

The U.S. Environmental Protection Agency sued DTE Energy in 2010 because the company replaced key boiler parts at its Monroe Unit 2 without installing pollution controls that are required whenever a utility performs a major overhaul. DTE said the project was only routine maintenance.

U.S. District Judge Bernard Friedman threw out the suit, saying EPA went to court too soon.

But the Sixth U.S. Circuit Court of Appeals overturned his decision Thursday. In a 2-1 ruling, the court says the law doesn't block EPA from challenging suspected violations of its regulations until long after power plants are modified.