The Department of Justice has filed an antitrust lawsuit against Visa, accusing the company of maintaining an illegal monopoly and thwarting competition.

According to the DOJ, Visa’s network handles more than 60% of the debit transactions in the US, resulting in more than $7 billion in fees annually. The complaint goes on to allege that Visa uses its market dominance to lock banks and merchants into exclusionary contracts, making it nearly impossible for companies to compete.

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For example, Visa wields its dominance, enormous scale, and centrality to the debit ecosystem to impose a web of exclusionary agreements on merchants and banks. These agreements penalize Visa’s customers who route transactions to a different debit network or alternative payment system. In so doing, the complaint alleges, Visa locks up debit volume, insulates itself from competition, and smothers smaller, lower-priced competitors. Visa also induces would-be competitors to become partners instead of entering the market as competitors by offering generous monetary incentives and threatening punitive additional fees. As the complaint alleges, Visa coopted the competition because it feared losing share, revenues, or being displaced by another debit network altogether.

Unfortunately, because debit card transactions are so popular in the US, Visa is in a position to charge billions in fees, effectively controlling both sides of the market—merchants and consumers.

“We allege that Visa has unlawfully amassed the power to extract fees that far exceed what it could charge in a competitive market,” said Attorney General Merrick B. Garland. “Merchants and banks pass along those costs to consumers, either by raising prices or reducing quality or service. As a result, Visa’s unlawful conduct affects not just the price of one thing – but the price of nearly everything.”

The DOJ says Visa so heavily penalizes partner companies for using competing payment networks that the vast majority don’t dare use anything but Visa, regardless of what benefits competitors may offer. The company also has allegedly made it a practice “to pay potential competitors to partner instead of innovating,” ensuring its stranglehold on the market is never disrupted.

“Anticompetitive conduct by corporations like Visa leaves the American people and our entire economy worse off,” said Principal Deputy Associate Attorney General Benjamin C. Mizer. “Today’s action against Visa reminds those who would stifle competition rather than competing on price or investing in innovation that the Justice Department will never hesitate to enforce the law on behalf of the American people.”

“Visa fears competition and innovation, and instead chooses unlawful cooperation and monopolization,” said Principal Deputy Assistant Attorney General Doha Mekki of the Justice Department’s Antitrust Division. “Visa abuses its power over its customers and buys off would-be rivals at the expense of American consumers, merchants, banks, and the competitive process itself. Today’s lawsuit holds Visa accountable for its conduct in a market that forms the backbone of American commerce.”

If the DOJ is successful in its case against Visa, the result could be a monumental change to the US financial industry.