The US Supreme Court heard arguments Tuesday in cases concerning how courts should determine the ownership of tax refunds paid to affiliated corporate groups and whether federal law preempts state law claims for the cleanup of hazardous waste beyond what the US Department of Environmental Protection (EPA) has ordered.

The first case, Rodriguez v. FDIC, involves a dispute between the parties representing competing interests of two failed companies in the collection of a $4 million tax refund. In 2010 United Western Bank—a wholly owned subsidiary of United Western Bancorp, Inc. (UWBI)—suffered $35 million in losses and sought to “carry back” those losses in 2011, entitling them to a $4 million refund. Tax law at the time allowed the bank to carry back its losses up to two years. However, at that time both the bank and its parent company UWBI were failing, prompting federal authorities to close the bank in January 2011 and appoint the Federal Deposit Insurance Corporation (FDIC) to serve as a third-party receiver and dispose of the bank’s remaining assets.

In March 2012, UWBI filed for Chapter 11 bankruptcy, with Simon Rodriguez serving as the court-appointed trustee. Litigation commenced with Rodriguez arguing that the pending $4 million tax refund was property of the UWBI bankruptcy estate, while the FDIC contended that the refund was the bank’s property. The bankruptcy court held that the refund was property of UWBI’s bankruptcy estate. However, both the district court and US Court of Appeals for the Tenth Circuit found the refund to be property of the bank.

The FDIC argued that Colorado contract law should govern and that because UWBI had a written contract with its affiliate United Western Bank to allocate any tax refund to the affiliate whose losses and income gave rise to the refund claim, that the $4 million should be the property of the bank.

On the other hand, Rodriguez argued that under Colorado law, the refund became property of UWBI upon receipt from the IRS, and that UWBI’s obligation to pay the bank was merely an unsecured claim in the underlying bankruptcy case.

The second case argued on Wednesday, Atlantic Richfield Co. v. Christian, considers whether federal law preempts state law claims for the cleanup of hazardous waste beyond what the EPA has ordered.

The case involves one of the first sites listed as a priority “Superfund” site under the 1980 Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), which was enacted to manage and clean up large-scale hazardous-waste sites.

The site was the Anaconda Co. Smelter in Montana and involved the spread of heavy-metals pollution across roughly 20,000 acres. The lawsuit was brought in 2008 by landowners within the polluted area who argue that the owner of the site, Atlantic Richfield, should be required to restore their property to its original condition. Atlantic Richfield completed all the work ordered by the EPA in 2016, but outside experts claim additional work is needed.

Petitioner Atlantic Richfield argued that CERCLA preempts any challenge to the EPA’s remedy and that the landowners are barred from seeking any remedial action without the EPA’s authorization.

The respondent landowners argued that nothing in CERCLA bars a “core exercise of state authority to vindicate private property rights” in state court and that the EPA is not so powerful as to bar the removal of a “shovelful of dirt from a private landowner’s backyard.”