This controversial move was his ticket to a lawsuit.

Airline Lufthansa recently sued a passenger who allegedly skipped a leg of his flight, claiming the person violated their terms and conditions and demanding roughly $2,400 in compensation. The apparent issue at hand was something called “hidden city” ticketing, a controversial practice that can help consumers save money on flights but that airlines dislike because it’s costly to them.

Here’s a real-life example of how hidden-city ticketing — where you book a flight and get off at the layover destination, rather than flying to the final destination — might save you money, from Travel & Leisure: Let’s say you want to go from Los Angeles to Charlotte, North Carolina. You might get a non-stop flight from Los Angeles to Charlotte for $553. But a flight from Los Angeles to Orlando, with a stop in Charlotte, might cost just $121. A passenger looking to save money might book the latter flight — go right from LA to Charlotte — and just never continue on to Orlando.

See also: Flight fees are on the rise — here’s how to avoid them

In the Lufthansa LHA, +4.56% case, the passenger reportedly booked an Oslo to Seattle flight with a layover in Frankfurt; he got out at Frankfurt and boarded a separate Lufthansa flight to Berlin there, according to court documents obtained by CNN.

Though that case was dismissed in a Berlin court in December, Lufthansa reportedly confirmed to CNN that they had “already filed the appeal against the decision”. Lufthansa declined to comment to Marketwatch on the case, citing the ongoing nature of the lawsuit.

This brings up several issues consumers should take note of:

Might other airlines crack down on this too? Adrian Brijbassi, the managing partner of travel rewards site Trippzy, says they might. Already, “several airlines have punished passengers who practice skip-lagging by removing them from loyalty programs,” he says — adding that this is likely to continue.

What’s more, this isn’t the first lawsuit on the topic. In 2015 United Airlines UAL, +0.82% and Orbitz filed a lawsuit against the founder of Skiplagged.com, a site that allows consumers to find hidden-city tickets, though a judge dismissed that case and Skiplagged.com is still up and running.

But Gabe Saglie, an anchor and producer at travel deals site ​Travelzoo, says “if Lufthansa prevails, it could well inspire other carriers to take action … the cost and the public image hit, though, could continue to work in travelers’ benefit.”

How much money can you save by practicing “hidden city” ticketing? Matt Guidice, who runs cheap flight service Matt’s Flights, notes that this “really depends” but it could be hundreds of dollars. In the Lufthansa case, the passenger allegedly saved more than $2,000.

Is this ethical? Some experts say no. “Hidden city cheaters make airfares more expensive for everyone who plays by the rules,” says George Hobica, the founder of airfare deals site AirfareWatchdog.com, who adds that he hopes Lufthansa wins its case. “They remind me of tax dodgers who hide their money in the Bahamas or other tax havens, causing honest people to pay more than their fair share.”

And Brijbassi notes that the practice may violate airline code-of-conduct policies. But “the detrimental impact on other travelers is the biggest reason we are against skip-lagging. It causes expense and inconvenience to others,” he says.

Bottom line: While this may be tempting to do, there are plenty of other ways to find cheap flights, says Saglie. “Price flights on other carriers, price flights into alternative/regional airports ([Burbank] and [Long Beach] instead of LAX, for example) and travel during days of the week or times of the year when airfare prices to their destination will drop.”