Ohio v. American Express Co.

American Express (Amex) (defendant) charged merchants higher fees than competitors but offered cardholders greater rewards, and its merchant agreements barred steering customers away from using Amex cards at checkout. The United States and several states (plaintiffs) sued, and the trial court, treating the merchant-fee side and cardholder-credit side as separate markets, found the antisteering provisions anticompetitive for raising merchant fees; the Second Circuit reversed, holding the credit-card market should be analyzed as one two-sided market, and the Supreme Court granted review.