Amazon’s vast third-party marketplace—millions of sellers listing billions of items—has long been the company’s growth engine. It’s also become the company’s legal lightning rod. On September 2, 2025, a federal judge in Seattle certified a nationwide class action on behalf of an estimated 288 million U.S. consumers who bought five or more new goods from third-party sellers on Amazon since May 26, 2017. The case alleges Amazon used pricing policies that kept sellers from offering lower prices elsewhere, inflating fees and ultimately raising consumer prices. Amazon denies wrongdoing and has already appealed. If it proceeds, this could be one of the largest consumer class actions by headcount in U.S. history.

At the heart of the U.S. suit—De Coster et al. v. Amazon.com Inc.—is a simple antitrust theory with complex marketplace ramifications: if a dominant platform prohibits third-party merchants from listing lower prices on rival sites, competition is chilled and prices stay high. Plaintiffs say Amazon enforced this through contractual and algorithmic pressure; Amazon counters that the challenged program ended in 2019 and that a class this large is unmanageable. The judge rejected that “too big to certify” argument at this stage, noting other courts have handled massive classes. What happens now is classic class-action choreography: further merits discovery and motion practice while the Ninth Circuit considers Amazon’s appeal of certification.

Pressure isn’t only coming from U.S. courts. In July 2025, the U.K.’s Competition Appeal Tribunal allowed two opt-out collective actions to proceed, together valued at up to £4 billion. One, led by competition law professor Andreas Stephan, seeks £2.7 billion on behalf of more than 200,000 third-party retailers, alleging Amazon’s “Buy Box” and logistics stack unfairly favor sellers who use Amazon’s own services. A separate consumer action seeks £1.3 billion over similar alleged abuses. Amazon disputes both claims, but the tribunal’s go-ahead signals real litigation risk in Europe’s second-largest e-commerce market.

Meanwhile, U.S. product-safety regulators have reshaped the liability landscape for goods sold by marketplace sellers but stored and shipped by Amazon. In July 2024, the U.S. Consumer Product Safety Commission (CPSC) issued a unanimous Decision and Order classifying Amazon as a “distributor” under federal safety law for certain hazardous third-party products—think defective carbon-monoxide detectors, non-compliant hair dryers, and flammable children’s sleepwear—sold via the Fulfilled-by-Amazon program. Being a “distributor” carries recall and notification duties that Amazon had argued should not apply to a platform operator. The CPSC followed up with a detailed remediation order in January 2025. Amazon has fought back in court, suing the CPSC over the recall directive and arguing the agency overstepped. Whatever the outcome, the message is clear: regulators expect Amazon to shoulder recall responsibilities when it controls storage and shipment.

Courts have been edging in that direction too. In Bolger v. Amazon (2020), a California appellate court held Amazon could be strictly liable for a defective third-party product (a replacement laptop battery) sold on its site and fulfilled through its logistics chain. The court’s reasoning: Amazon had placed itself squarely in the distribution stream and exercised control akin to a retailer. The ruling doesn’t bind other states, and courts remain divided, but Bolger has become a touchstone in debates over whether platforms are mere conduits or de facto sellers when they warehouse and ship goods.

Seller-side litigation is also growing. In 2025, a suit filed in the Southern District of Florida by a large cohort of marketplace merchants attacks account suspensions, alleged mishandling of inventory, and compliance burdens tied to the federal INFORM Consumers Act. For sellers—many of whom run thin-margin operations—the difference between “active” and “suspended” can be existential. Amazon typically responds that enforcement is necessary to protect buyers and platform integrity, and that sellers have appeal avenues. The Florida case tests how far a platform can go before enforcement becomes arbitrary or anticompetitive.

Why these cases matter (and to whom): for consumers, the U.S. antitrust class action targets the prices you pay when a single platform sits at the center of online retail. A plaintiffs’ win could mean refunds, but more importantly it could reset how Amazon structures seller fees and price-matching policies—changes that ripple across the entire e-commerce stack. For sellers, the U.K. cases (and the Florida seller suit) go to the core of marketplace bargaining power: access to the Buy Box, dependence on Fulfilled-by-Amazon, and the ability to set prices across channels without penalty. For regulators, the CPSC’s distributor ruling is a template for making marketplaces responsible for recalls when they control fulfillment, a significant shift from the early “we’re just a platform” era.

What to watch next: in the U.S., keep an eye on Amazon’s appeal of certification in the De Coster case and any summary-judgment rulings that clarify whether the challenged pricing constraints persisted after 2019. In the U.K., the CAT’s certification means both retailer and consumer actions move toward trial, with procedural steps (expert reports, disclosure, and potential settlement discussions) likely to define the timeline. On safety, Amazon’s suit against the CPSC could either narrow or cement the agency’s power to force marketplace-wide recall remedies. And in the background, individual product-liability suits will continue probing when a platform becomes indistinguishable from a seller for purposes of consumer protection law.

Sources

• Reuters — “Amazon must face US nationwide class action over third-party sales” (Sept. 2, 2025). Reuters
• Reuters — “Amazon faces UK lawsuits worth up to $5.4 billion from retailers, consumers” (July 24, 2025). Reuters
• U.S. Consumer Product Safety Commission — Decision and Order finding Amazon a “distributor” for hazardous third-party products (July 30, 2024). U.S. Consumer Product Safety Commission
• U.S. Consumer Product Safety Commission — Final Order outlining remediation plans (Jan. 17, 2025). U.S. Consumer Product Safety Commission
• Associated Press — “Amazon sues CPSC over recall order for hazardous products” (Apr. 2025). AP News
• Bolger v. Amazon.com, LLC, 53 Cal.App.5th 431 (Cal. Ct. App. 2020) — case text. Justia
• Avenue7Media summary of Florida sellers’ lawsuit alleging suspensions and compliance harms (June 24, 2025).