Sure thing. In bullet point form: - Congress, when it legislates within its constitutional domain of authority, has the power to override ("preempt") contrary

Sure thing. In bullet point form: - Congress, when it legislates within its constitutional domain of authority, has the power to override ("preempt") contrary state law---and most of the classic legal principles that we inherited from England, such as the rules of contract law and tort (personal injury, fraud, other kinds of civil wrongs) are matters of state law. - when Congress enacted the Airline Deregulation Act, they chose to preempt state law having basically anything at all to do with how airlines ran their operations. - The plaintiff in the case I linked had just been randomly kicked out of Northwest Airlines's frequent flier policy, lost all her status, etc. He sued, claiming that they cancelled his policy for dishonest, bad-faith reasons (to cut costs before the Delta merger). - Even though the ToS of the frequent flier program essentially said "we can kick you out for any reason," state law added an "implied covenant of good faith and fair dealing," which required, essentially, that contracting parties not abuse terms like that in order to egregiously rip one another off---which is what the plaintiff alleged. The implied covenant of good faith and fair dealing is a pretty foundational contract law idea that lots of people think is fairly important. - The Supreme Court interpreted Congress's intent in the airline deregulation act to include preempting the covenant of good faith and fair dealing, thus implying that all kinds of abusive airline behavior, if it was strictly within the written words of the airline contract, even if normal state contract law wouldn't enforce it, would be perfectly hunkry dory. Plaintiff loses.