I live in Philadelphia and if I want to visit a friend in Chicago for a weekend, it will cost me several hundred dollars for a round-trip ticket on U.S. Airways. For significantly less money, I could book what’s known as a “hidden city” ticket from Philadelphia to Orlando via Chicago, and then just get off the plane when it stops in Chicago. Most airlines ban the practice, but there’s not much they can do to stop it. They can, however, sue to stop a website from promoting and booking these verboten fares.

Skiplagged.com is a site that lists and is supposed to allow you to book hidden city fares (though all of our attempts to reserve tickets failed), and is now the subject of a lawsuit [PDF] filed in federal court by both United Airlines and travel-booking service Orbitz.

The plaintiffs accuse Skiplagged and its owner of “intentionally and maliciously” interfering with their business by “promoting prohibited forms of travel” and inducing “breach of Orbitz Worldwide’s travel agency contracts with commercial airlines and of United’s customer contractual relationships.”

Most airlines forbid passengers from booking travel to somewhere other than their intended destination. Additionally, the deals that travel agents and booking services make with airlines generally include a ban on knowingly allowing a customer to purchase a hidden city fare.

The plaintiffs claim that Skiplagged and its owner are aware of this prohibition and still not only advertised the fares but also then directed users to the United and Orbitz websites to purchase the tickets.

The airline and the travel site claim that this direct-linking to their online booking portals falsely gave the impression that the plaintiffs were affiliated with Skiplagged.

“To the average internet user of Skiplagged, the transition from the Skiplagged site to Orbitz’s website is seamless and strongly suggests an affiliation or identity between Skiplagged and Orbitz that does not exist,” reads the complaint. “By creating a website that operates in much the same manner as an online travel agency, and by linking that site to Orbitz’s site, [the defendant] is attempting to confuse and mislead the public into believing that his website, and the “hidden city” ticketing it employs, is done with the approval (if not the outright authorization and sponsorship) of Orbitz and the airlines.”

Orbitz claims that the Skiplagged owner “expressly agreed not to engage in this conduct when he entered into an affiliate agreement with Orbitz, LLC in early 2013.” That agreement has subsequently been terminated. Additionally, the complaint claims that the defendant “has taken steps to try to hide from Orbitz and United his continued bad conduct and breach of his promises to stop.”

United says that when it demanded that all of its trademarks and content be deleted from the site, Skiplagged initially responded that it would do so. But instead, according to the complaint, Skiplagged replaced United’s name with a “Flight Censored” label, and a note reading “Sorry for the inconvenience, but United Airlines says we can’t show you this information.”

Additionally, United claims that Skiplagged continued to list the airline’s flights, but with slightly altered departure times so that the content was not identical to that published on the United site.

Among the violations alleged by the plaintiffs are violation of the Lanham Act’s prohibition against false affiliation, tortious interference, breach of contract, and misappropriation. The plaintiffs are seeking damages and asking the court to issue an injunction blocking Skiplagged from listing and offering hidden city fares.

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