On June 13, 2016, the Supreme Court of the United States denied an appeal from states and industry in Michigan v. EPA regarding the Mercury & Air Toxics Standards (MATS). The petitioners appealed the D.C. Circuit’s decision to leave MATS in effect while the court remanded the rule to U.S. EPA to revise its “appropriate and necessary” determination, which was a statutory prerequisite to U.S. EPA’s authority to issue the rule. The petitioners argued that by leaving MATS in effect the D.C. Circuit “thwarted” the Supreme Court’s 2015 decision, which held that EPA improperly refused to consider costs in making its appropriate and necessary determination. The Supreme Court did not explain its reasoning for denying the appeal.