Alabama-based Olin Corporation (plaintiff) manufactured commercial chemicals that contaminated segments of Olin’s property, referred to as OU-1. The Environmental Protection Agency (EPA) (plaintiff) filed suit in federal district court seeking an order to require Olin to clean up OU-1 pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Prior to approving a consent order agreed to by the parties in which Olin agreed to pay all costs associated with the cleanup, the district court required the parties to address whether the U.S. Supreme Court’s holding in United States v. Lopez, 514 U.S. 549 (1995), had any effect on the consent order. Olin responded that CERCLA could not constitutionally impose liability for conduct predating the statute’s enactment. The district court agreed and dismissed EPA’s suit. EPA appealed.