A proposed class action filed March 24, 2026, alleges that Costco Wholesale passed the costs of now-invalidated International Emergency Economic Powers Act tariffs onto consumers and stands to collect hundreds of millions, potentially exceeding $1 billion, in government refunds without reimbursing those shoppers [1]. The complaint advances an unjust enrichment theory, arguing that Costco should not retain the benefit of both elevated consumer prices and incoming refund payments tied to tariffs courts have since voided [1][2].
The lawsuit follows a February 20, 2026, Supreme Court ruling in Learning Resources, Inc. v. Trump, which held that the IEEPA tariffs at issue were unlawful [1][2]. IEEPA grants the president broad authority to regulate commerce in response to declared national emergencies, and the Trump administration had invoked that authority as the legal basis for a sweeping tariff regime. The Supreme Court's decision effectively nullified those charges, triggering a refund process for importers who paid duties into the U.S. Treasury under the invalidated orders. Costco, as a large-volume importer, is positioned to receive substantial refund payments from that process [2].
The Illinois-filed complaint contends that consumers who paid higher prices on Costco merchandise during the period the tariffs were in effect have a cognizable claim to a share of any refund the company receives [2]. Plaintiffs argue the retailer's retention of both the consumer price premiums and the forthcoming government refunds constitutes a double recovery at shoppers' expense. The case presents a novel application of unjust enrichment doctrine, one that would require courts to trace the economic relationship between import-level tariff costs, retail pricing decisions, and downstream refund flows.
No ruling on class certification has been entered, and Costco has not publicly responded to the complaint as of the available reporting [1][2]. The outcome will turn in part on whether plaintiffs can establish the requisite causal link between specific tariff-inflated prices paid by individual consumers and the aggregate refund amounts Costco expects to receive. Similar theories could, if sustained, expose other major retailers facing comparable refund windfalls to parallel litigation. The case is being watched as an early test of whether the legal consequences of the Supreme Court's IEEPA ruling will extend beyond importers to retail consumers.