It has been alleged for years that Amazon has misused its economic dominance and harmed fair competition, and now the US government and 17 states have filed a landmark monopoly case against the online giant.

It marks the government’s sharpest attack yet on Amazon, which began as a book seller on the internet but has since become known as “the everything store,” after expanding into selling a wide range of consumer products, building a global logistics network and becoming a leader in cloud computing. In addition to selling a wide variety of consumer products, Amazon has also become a powerhouse in other technologies.

According to the 172-page complaint, Amazon unfairly promotes its own platform and services to the detriment of third-party sellers.

To qualify for Amazon’s best seller benefits, referred to as “Prime” eligibility, sellers on Amazon’s platform must purchase Amazon’s in-house logistics services. Furthermore, it claims Amazon undercuts its competitors by forcing sellers to list their products on Amazon at the lowest prices anywhere on the web, rather than allowing them to sell on competing marketplaces.

California’s attorney general filed a separate lawsuit against Amazon last year over this practice.

The FTC alleges that Amazon’s dominance in e-commerce forces sellers to accept Amazon’s terms, resulting in higher prices and a worse shopping experience for consumers. The FTC also found that Amazon ranks its products higher than those sold by third parties in marketplace search results.