On June 25, 2018, the Supreme Court upheld a Second Circuit opinion that American Express did not violate antitrust law by prohibiting merchants from encouraging customers to use non-American Express credit cards. As part of their agreements with American Express, merchants were required not to steer customers to use non-American Express credit cards (merchants could still express a preference for cash, checks or debit cards). The state of Ohio, the United States, and several other states brought suit alleging that these “anti-steering” provisions violated Section 1 of the Sherman Act as an “unreasonable restraint of trade.” The Supreme Court opined that the relevant market in which to assess the anti-steering provisions is two-sided; that is, courts must consider competitive effects and benefits on both the consumer payments and payment processing sides of the transactions.