Ohio v. American Express Co.

Payment networks set rules for millions of merchants. Anti-steering clauses ban subtle nudges like 'use debit to save us money.'

Visa and Mastercard settled with the DOJ and changed rules; Amex fought on.

Courts debated whether to look only at merchant harms or also cardholder rewards and brand value.

Justice Thomas's majority opinion said plaintiffs must show net harm across the platform—a high bar that shielded Amex's business model.

Two-sided market theory affects tech platforms, not just credit cards.

Merchants lost a tool to push back on swipe fees through customer steering.

Contrasts with EU and DOJ wins against Visa/Mastercard restraints on different records.

Amex anti-steering agreements were unreasonable restraints of trade.

Merchants could not reduce acceptance costs by steering to lower-fee networks.

Network market power made vertical restraints harmful.

Amex argued its model funds premium rewards and fraud protection for cardholders.

It said steering bans preserve brand consistency and investment in cardholder benefits.

Amex maintained merchants voluntarily accept its cards for valuable customers.

Stores still rarely encourage you to pick a cheaper card at Amex-heavy merchants.

Rewards cards remain subsidized partly by merchant fees upheld here.

Later cases distinguish platform markets carefully after Amex precedent.