In United States v. Atlantic Research Corp., 127 S. Ct. 2331 (2007), the United States Supreme Court cleared up one aspect of hazardous waste law while making a mess of another. The clarity came from a Court mandate that any private party who incurs costs by remediating a hazardous waste site can make out a cost recovery claim to recoup expenses. In sum, the Court has matched the plaintiff (private party remediator) to the cause of action (cost recovery). Now, however, a question arises: Who are the defendants? Perhaps, as has been suggested, the defendants can include parties who previously entered into settlement regarding the waste site—parties who attempted to resolve their liability in exchange for immunity from further litigation. Indeed, the Court’s decision has “cast[] a cloud of doubt” over these settlements and may be “destroy[ing] the expectations of literally thousands of [parties].”