The contracts with merchants prohibited them from accepting other forms of payment. https://www.justice.gov/archives/opa/pr/justice-department-sues-visa-monopo

The contracts with merchants prohibited them from accepting other forms of payment. https://www.justice.gov/archives/opa/pr/justice-department-sues-visa-monopolizing-debit-markets https://www.justice.gov/archives/opa/pr/justice-department-s...