The imposed a “web of exclusionary agreements” that penalize merchants who use alternative payment processors, the Justice Department said.

The Justice Department is accusing Visa of running a debit card monopoly that has hiked fees for American consumers and businesses.

The Department of Justice (DOJ) filed an antitrust lawsuit against Visa. The lawsuit alleges that the financial firm holds a monopoly over debit network markets allowing it to charge banks and markets with exorbitant fees that get passed onto consumers and keep rival companies like PayPal and Square from competing on their level.

The U.S.’s largest card network blocked rivals through payments and higher fees levied on merchants, the government says.