The U.S. Supreme Court declined to review a pair of decisions out of the Minnesota Supreme Court which held that employers cannot be required to reimburse workers for marijuana used to treat on-the-job injuries because the substance is illegal under the federal Controlled Substances Act. The cases are Bierbach v. Digger's Polaris and Musta v. Mendota Heights Dental Center et al, 965 N.W.2d 312 (Minn. 2021).

In both cases, a Workers' Compensation Judge awarded the injured worker reimbursement for medicinal marijuana expenses incurred to treat their work-related injuries. In both cases, the Minnesota Workers' Compensation Court of Appeals upheld the decision of the Judge and declined to address the conflict of law between the Federal Controlled Substances Act (CSA) and Minnesota's Medical Marijuana law (MCTRA), stating that the appeals court lacked the appropriate jurisdiction to address the conflict.

The Supreme Court of Minnesota held in both cases that there was a conflict between the CSA and MCTRA, and reversed the underlying decisions directing reimbursement of medical marijuana to injured Minnesota workers. The court in the Bierbach case concluded that the Federal CSA statute pre-empted the MCTRA. The order directing reimbursement was reversed. The court in Musta vacated the order of the Judge directing the medical marijuana reimbursement. That court based its decision on a conclusion that the requested reimbursement would cause the carrier to aid and abet illegal activity, paying for federally illegal drugs. The court stated that it was impossible to comply with both MCTRA and the CSA, and the Federal law preempts the MCTRA, state law. The court specifically stated, "we express no opinion on whether the CSA pre-empts any component of Minnesota's medical cannabis program." The court declined to address all three types of conflict preemption. A dissent was authored in both cases.