In this case, skycaps who worked at US airways terminals brought state-law claims against the airline for imposing a $2 fee for curbside checking that captured much of the skycaps’ compensation from tips. The district court held that the skycaps’ claims are preempted by the Airline Deregulation Act (ADA), which prohibits states from enacting or enforcing “a law, regulation, or other provision having the force and effect of law related to a price, route, or service of an air carrier . . . .” 49 U.S.C. § 41713(b)(1). On appeal to the First Circuit, Public Citizen filed an amicus in support of the skycaps, arguing that common-law is not “a law, regulation, or other provision” within the meaning of the ADA, and that the ADA’s preemption provision therefore does not preempt common-law claims.