On December 3, 2019, the U.S. Supreme Court will hear argument in Atlantic Richfield Co. v. Christian, et al., a case that raises the question of whether landowners may bring state-law causes of action to force Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) parties to go beyond what the Environmental Protection Agency (EPA) has ordered them to do. CERCLA allows EPA to investigate and clean up contaminated sites and to recover its costs from persons and entities (potentially responsible parties, or PRPs) that have a connection to these sites. When faced with government action at a site, PRPs sometimes elect to perform these investigations and remedial actions themselves. In either case, EPA decides on a remedial action, allowing PRPs to have some understanding of the costs they are facing. Atlantic Richfield arises out of contamination over a wide area in Montana caused by the Anaconda Smelter, which operated for almost a century. After Atlantic Richfield agreed to clean up the site and EPA approved its remedial action plan, a group of property owners within the site boundary sued Atlantic Richfield in state court. The property owners alleged that they were entitled to damages under state law that would allow them to restore the land to its original condition. Atlantic Richfield argued that CERCLA barred the landowners’ claim, but the Montana courts disagreed, teeing the issue up for Supreme Court review. Before the Court, the parties will address three primary issues: first, whether the landowners’ plan to restore the land to its original condition would go beyond EPA’s remedial action plan and, therefore, run afoul of the CERCLA Section 113(h) ban on “pre-enforcement” review, which restricts challenges to EPA response actions until EPA itself seeks to enforce its cleanup plan or after a cleanup is completed; second, whether the landowners are themselves PRPs and thus cannot act without EPA approval; and third, whether CERCLA preempts the property owners’ state-law response claim. Atlantic Richfield has the potential to significantly affect future CERCLA litigation. PRPs facing CERCLA’s unforgiving and strict liability regime have relied on the proposition that once EPA decides on a remedy and the cost of that remedy is ascertained, the scope of liability is generally set. If accepted, the landowners’ theory in Atlantic Richfield could expose PRPs to significant uncertainty in cost and finality of site remediation.