On Monday, June 29, 2015, the U.S. Supreme Court issued a 5-4 opinion in Michigan v. EPA, holding that the EPA must consider costs to the regulated industry in determining whether limiting mercury in power plant emissions is “appropriate and necessary”, in the words of the Clean Air Act. The decision reverses a ruling of the D.C. Circuit Court upholding EPA’s mercury regulation and sends the litigation back to the Circuit Court for further proceedings. The specific regulation at issue is known as MATS (mercury and air toxics standards) and requires power plants to comply with emission limits on mercury… Read more