American Airlines v. Wolens
In American Airlines v. Wolens, 513 U.S. 219 (1995), the Supreme Court held that while States cannot impose their own substantive standards on air carriers with respect to "rates, routes, or services" under Title 49, section 41713 (b) of the United States Code, they are not prevented "from affording relief to a party who claims and proves that an airline dishonored a term the airline itself stipulated." Wolens, 513 U.S. at 232-233.
"This distinction between what the State dictates and what the airline itself undertakes confines courts, in breach-of-contract actions, to the parties' bargain, with no enlargement or enhancement based on state laws or policies external to the agreement." Id. at 233.