The US Supreme Court decided unanimously that an airline had the right to dump a frequent flier who complained too much.
The decision allows airlines to have sole discretion to drop frequent fliers.
The case involved Rabbi Binyomin Ginsberg, who was ousted from Northwest Airlines' WorldPerks loyalty program for complaining too often about getting bumped from flights and repeatedly seeking compensation the airline considered unfair.
The airline argued that frequent-flier programs operate at the sole discretion of the airline. Airlines said they can't tailor their programs to a patchwork of consumer laws in 50 states.
In overturning the Ninth US Circuit Court of Appeals, Justice Samuel Alito wrote that travellers have protection from being mistreated because they could sue for possible breach of contract, just not for covenants that Ginsberg had argued were implied by participating in a loyalty program.
"They can avoid an airline with a poor reputation and possibly enroll in a more favorable rival program," Alito wrote in the 18-page decision. "Moreover, the Department of Transportation has the authority to investigate complaints about frequent flyer programs."
Adina Rosenbaum, a lawyer from Public Citizen who represented Ginsberg, said the court didn't block breach-of-contract lawsuits against airlines, but that the decision could still hurt consumers.
"Today's decision gives airlines greater freedom to act in bad faith in performing their contracts with consumers, to the detriment of the millions of consumers," Rosenbaum said.
Chris Nemeth, a partner at McDermott Will & Emery law firm in Chicago, who works on contract disputes, called the case a qualified victory for the airlines because the court left open the possibility that a traveller could still sue over a breach of contract.
Nemeth said he didn't expect travellers to see changes in how loyalty programs work, except perhaps to explicitly say that airlines won't be bound by covenants for good faith and fair dealing that aren't stated in the agreements.
"I don't think passengers can expect any significant differences at all in the way that airlines treat passengers or in the way that the loyalty programs work," Nemeth said.
Northwest, which has since become part of Delta Air Lines, dumped Ginsberg in June 2008 after he complained 24 times in eight months. He flies 75 times a year to lecture, so he enjoys the benefits of loyalty programs.
Rosenbaum argued that airlines should be forced to act in good faith, even when those "implied covenants" aren't spelled out in the contracts for loyalty programs.
But the 1978 Airline Deregulation Act law prevents regulation dealing with the "price, route or service of an air carrier."
Paul Clement, a former US solicitor general representing Northwest, said airlines wouldn't be crazy enough to dismiss their most lucrative and loyal customers. He said rather than filing lawsuits, passengers can file complaints with the Transportation Department, which investigated 289 cases in 2012.