Federal Judge Certifies Historic 300-Million-Consumer Class Action Against Amazon Over Price Inflation

A federal judge has officially certified the largest consumer class-action lawsuit in U.S. history, allowing approximately 300 million Americans to sue Amazon for alleged price-fixing.[1][2]

The lawsuit, De Coster et al. v. Amazon.com, Inc., centers on a simple but massive claim: Amazon uses its market dominance to force third-party sellers to artificially inflate their prices across the entire internet.[1]

U.S. District Judge John H. Chun of the Western District of Washington certified the class, which encompasses anyone in the United States who purchased five or more new, physical goods from third-party sellers on Amazon's marketplace on or after May 26, 2017.[1]

With the opt-out deadline approaching on August 31, 2026, and a trial set for June 2027, the stakes are unprecedented. Plaintiffs' economic experts estimate the alleged conduct has affected roughly 34 billion individual transactions.[1]

To understand the lawsuit, one must understand how Amazon's third-party marketplace operates. Amazon hosts roughly 2.3 million active third-party sellers, who account for the vast majority of the goods sold on the platform.[4]

These sellers pay Amazon steep fees for the privilege of reaching its massive customer base. According to the complaint, sellers pay either a monthly subscription or a per-item fee, plus a referral fee that typically hovers around 15% of the transaction price.

Because Amazon's fees are generally higher than those of competing platforms like eBay or independent storefronts, sellers would naturally prefer to offer their products at a lower price elsewhere. However, the lawsuit alleges that Amazon's policies make this financially impossible.

The mechanism at the heart of the dispute is Amazon's anti-discounting policy, which plaintiffs describe as a platform most-favored nation restraint.

Until 2019, Amazon explicitly enforced a Price Parity Clause in its seller agreements, which legally barred merchants from listing their goods at a lower price on any other website.[2]

Although Amazon removed the explicit clause following regulatory scrutiny, plaintiffs allege the company simply replaced it with an automated enforcement mechanism tied to the Featured Offer, commonly known as the Buy Box.[4]

The Buy Box is the crucial Add to Cart button on an Amazon product page. Winning the Buy Box is essential for a seller's survival, as it drives the overwhelming majority of sales for any given item.[4]

According to the complaint, Amazon's algorithms constantly scrape the internet—including sites like Walmart, Target, and direct-to-consumer stores—to monitor sellers' prices.

If a seller lists a product for even one cent less on a competing website, Amazon allegedly penalizes them by immediately revoking their Buy Box eligibility or burying their product in search results.

Faced with the threat of losing their Amazon sales, sellers are effectively forced to raise their prices on all other platforms to match the higher price they must charge on Amazon to cover the 15% referral fee.[2]

This dynamic, plaintiffs argue, creates an artificial price floor across the entire U.S. e-commerce sector. Consumers end up paying the Amazon tax regardless of whether they shop on Amazon, Walmart, or an independent retailer's site.[2][4]

Amazon has strongly denied the allegations. In its legal filings, the company argues that its pricing policies are designed entirely to benefit consumers by ensuring that Amazon shoppers always receive the most competitive prices available.[1]

The retail giant also fought aggressively against class certification, arguing that a class of 300 million people is inherently unmanageable and that individual purchasing contexts vary too widely to be grouped into a single lawsuit.[4]

Judge Chun rejected that argument, noting that federal courts have successfully managed class actions of this scale before, and ruled that the core question of whether Amazon's policies constitute an illegal restraint of trade applies uniformly to all buyers.[1]

If the plaintiffs succeed at the 2027 trial, the financial damages could reach into the billions. More importantly, a ruling against Amazon could force the company to fundamentally restructure its marketplace rules.[3]

Such a restructuring could finally break the internet's invisible price floor, allowing third-party sellers to freely discount their goods on competing platforms and ushering in a new era of genuine price competition for American consumers.[3][4]