Judge certifies class in Amazon class action alleging high third-party prices

Elizabeth De Coster and four other consumers filed a class action lawsuit alleging Amazon.com Inc. of using its grip on online retail to keep prices high for shoppers who buy from third-party sellers. They filed the case in 2021 in the U.S. District Court for the Western District of Washington, and on Aug. 6, 2025, a federal judge certified it as a class action that could cover hundreds of millions of people.

The lawsuit alleges Amazon charges third-party sellers steep fees then blocks those sellers from offering lower prices anywhere else, passing the added cost on to consumers.

Who are the class members?

The court certified a class including everyone in the United States who bought five or more new physical goods from third-party sellers on Amazon's marketplace on or after May 26, 2017. Used items, digital goods and prescription purchases do not qualify.

The plaintiffs' economics expert estimated Amazon's conduct affected around 300 million consumers and roughly 34 billion transactions. The The plaintiffs claim Amazon violated the Sherman Act, the main antitrust law in the U.S.

Amazon's market dominance and seller fees

Amazon operates one of the world's biggest online marketplaces, listing about 237 million products and hosting roughly 2.3 million active third-party sellers. To sell there, merchants pay either a $39.99 monthly fee or $0.99 per sale fee plus a referral fee of about 15% on each transaction, according to the lawsuit.

Plaintiffs contend those fees run well above what rivals like eBay charge and that sellers recover the difference by raising prices. The complaint estimates Amazon's share of what it calls the" online retail marketplaces market" at about 72%.

Amazon's alleged pricing policies

The plaintiffs allege Amazon has an anti-discounting policy that works like a price floor and prevents sellers from undercutting their Amazon prices elsewhere. Lawyers describe it as a "platform most-favored nation" restraint.

The complaint says Amazon enforced it through five overlapping policies:

  • Price parity clause, which barred lower prices on other sites until Amazon dropped it in March 2019
  • Select competitor featured offer disqualification, which removes a seller from the Buy Box for pricing even a cent lower elsewhere
  • Amazon's standards for brands, a 2018 program requiring competitive pricing at least 95% of the time
  • Seller code of conduct, which Amazon clarified in 2021 to bar off-Amazon discounts that steer shoppers away
  • Marketplace fair pricing provision, which Amazon adopted in November 2017 to penalize sellers priced far higher on Amazon than elsewhere

The plaintiffs claim Buy Box is the prominent add-to-cart button that drives most of the marketplace's sales and losing it can hurt a seller's revenue.

What the evidence allegedly shows

The plaintiffs claim a dedicated Amazon team tracked prices across thousands of outside websites and punished sellers who sold their goods for lower amounts. The lawsuit states economics expert Parag Pathak found seller compliance held around 80% before and after Amazon removed the price parity clause. The plaintiffs argue this shows the newer policies did the same work.

Pathak also reportedly found prices on rival sites rose about 4% in the week after a seller lost the Buy Box. The complaint highlights Jet.com, a marketplace whose prices ran roughly 9% below Amazon's before Walmart bought it in 2016 and shut it down in 2020, as a rival the policy undercut.

The plaintiffs quote one internal Amazon message in which an employee noted sellers could see the approach as "price-fixing."

What the case means for Amazon shoppers

No money is available now, and there is no settlement or claims process. The plaintiffs still have to prove their case at trial, which the court has set for June 14, 2027. Anyone who fits the class stays in automatically unless they opt out by Aug. 31, 2026, which is the only way to keep the right to sue Amazon separately over these claims.

The case website includes the court filings and more details.