Texas prodded Aviall Services to clean up contaminated property bought from Cooper Industries. Aviall sued in federal district court to force Cooper to pay some of the clean up costs. Aviall claimed it could sue Cooper under the federal Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). Cooper admitted to being a potentially responsible party (PRP), but claimed it was not liable because Aviall was never sued to clean up the land and had no federal requirement to do so. The district court and a panel for the Fifth Circuit Court of Appeals ruled against Aviall. The entire appellate court reversed and ruled CERCLA does not require a PRP to first be sued before seeking clean up funds from other PRPs.