Illinois Corporate Travel, Inc., Doing Business as McTravel Travel Services v. American Airlines, Inc., and Ivi Travel, Inc.

EASTERBROOK, Circuit Judge.

American Airlines would like to ban discounting by the firms that sell its tickets, but a prohibition cannot be enforced. Under-the-table discounts, rebates by “captives” (travel subsidiaries of the firms whose employees are traveling), and tie-in sales (packages of air travel and other services such as hotels, with the price reduction on the air fare allocated for bookkeeping purposes to the hotel or car rental) are endemic. American decided to demand only what it was prepared to enforce: it issued an Addendum to the agreement all travel service operators must sign…