Several major US airlines and their lobbying group sued the US Transportation Department-bsp-bb-link> over new regulations mandating up-front disclosure of certain fees, in a fight over rules the agency says could mean big savings for travelers.

The lawsuit was filed Friday at the 5th US Circuit Court of Appeals by industry trade group Airlines for America-bsp-bb-link> and the carriers, including American Airlines, Delta Air Lines, United Airlines and JetBlue Airways. They claim the department overstepped its legal authority in issuing the new requirements and called them “arbitrary, capricious” and “an abuse of discretion.”

Airlines for America called them “a bad solution in search of a problem.”

The final rules, unveiled…