Montana law allows property owners whose property has been contaminated by someone else to file a lawsuit for damages in the amount of the costs the property owners incur to remove the contaminants. Property owners in the vicinity of ARCO’s Anaconda Smelter in Montana sued ARCO, for the cost of removing contaminants deposited on their property by the Smelter. ARCO had conducted some remediation under a CERCLA remediation plan approved by EPA, and it argued that the CERCLA preempted the property owners’ state-law damages remedy to the extent it provided an additional remedy for environmental remediation. The Montana Supreme Court disagreed, and the U.S. Supreme Court granted review.
In the Supreme Court, Public Citizen filed an amicus brief arguing that CERCLA’s anti-preemption provisions foreclose the implied preemption arguments made by ARCO. On April 20, 2020, the Supreme Court issued its decision in the case. The Court did not accept the broad preemption arguments made by ARCO and the Solicitor General that were addressed in Public Citizen’s brief. The Court held, however, that the property owners were “potentially responsible parties” under CERCLA, and therefore required to obtain federal approval for any remediation activities, including any remediation that the owners sought to undertake using a damages award.