In December 2008, a containment dike failed at a fossil fuel plant owned and operated by the Tennessee Valley Authority (TVA), spilling approximately 5.4 million cubic yards of coal-ash sludge onto adjacent lands. The TVA entered into a contract with Jacobs Engineering Group that designated Jacobs as TVA’s “prime contractor providing project planning, management and oversight to assist TVA in overall recovery and remediation” associated with the spill. Individuals who worked on the coal-ash cleanup, along with some of their spouses, brought this case against Jacobs, alleging that Jacobs exposed workers to hazardous materials in an unsafe manner. Jacobs moved to dismiss, contending that it had “derivative sovereign immunity” under Yearsley v. W.A. Ross Construction Co., 309 U.S. 18 (1940). The district court granted the motion. On appeal, the Sixth Circuit reversed, holding that Yearsley immunity is not jurisdictional in nature and, therefore, that the district court should have considered Jacobs’s motion for failure to state a claim under Federal Rule of Civil Procedure 12(b)(6), instead of for lack of subject-matter jurisdiction under Federal Rule of Civil Procedure 12(b)(1). Jacobs sought review in the Supreme Court, where Public Citizen served as co-counsel for the plaintiffs. On January 25, 2016, the Supreme Court denied the petition.