On Jan. 22, the budget airline quietly made changes to its contract of carriage, which lays out rules and expectations for passengers, as well as a collection of obligations and terms for reservations, fares, baggage, refunds, and schedule changes. 

Spirit Airlines updated its conduct and condition section of the contract, specifying a passenger would not be permitted to board and could be asked to leave an aircraft if they’re “inadequately clothed,” which includes see-through clothing, as well as exposed breasts, buttocks, or other private parts. 

Additionally, the budget airline disallows customers passage if they’re wearing clothing or have body art that is “lewd, obscene, or offensive in nature.” It does not provide specific definitions or examples.

Spirit Airlines didn’t immediately respond to Fortune’s request for comment about the policy updates and why they were made. 

While it’s “reasonable for airlines to have basic standard requirements appropriate for a shared public setting,” the vague definitions of offensive or inadequately clothed “risk inconsistent enforcement and can lead to passenger dissatisfaction or even legal disputes,” says Joe Cronin, president of International Citizens Insurance, which provides travel insurance plans.

Spirit Airlines’ change in policy could’ve been precipitated by three Spirit Airlines passengers sharing that they had been kicked off of a flight in October 2024 for wearing crop tops. 

Tara Kehidi was with her friend Teresa Araujo on a flight from LAX to New Orleans, and both were wearing crop tops with “just like a little bit of stomach showing,” Kehidi told ABC News. Kehidi alleged that a male flight attendant approached her and Araujo and told them to “put something on.”

Kehidi said she and Araujo then asked to see the dress code for the airline. Another passenger sitting in front of them, Carla Hager, overheard the altercation and said it was too hot on the aircraft for them to wear sweaters. Hager was also wearing a crop top, and insisted that if Kehidi’s and Araujo’s outfits were inappropriate, then hers was too.

“And I was like ‘so if they’re kicking you off the flight, then they’re also going to have to kick me and my toddler off of the flight’,” Hager told ABC. 

And with that, the three adults and Hager’s toddler were kicked off the flight. 

Before Spirit Airlines updated its contract of carriage on Jan. 22, it issued the following statement to ABC:

“Our contract of carriage, a document all guests agree to upon making a reservation with us, includes certain clothing standards for all guests traveling with us. We are investigating the matter, and we are in contact with the guests about their experience.”

Can airlines dictate what passengers wear?

While it’s not uncommon for airlines to have rules and expectations for passenger conduct, Spirit’s appears to be more specific than others, Jennifer Yellin, senior editor with Points Path, a browser extension that helps customers find lower prices for travel, told Fortune.

For instance, American Airlines requires passengers to “dress appropriately,” noting that bare feet aren’t allowed. Hawaiian Airlines, fittingly, states that “speedos and bikini bottoms are not allowed.”

“Just like a restaurant or a club can require a dress code, an airline can dictate a certain level of attire, so long as the rule is applied fairly and doesn’t discriminate against a protected class,” Yellin said. 

And perhaps this policy could have come in handy ahead of Kehidi and Hager boarding their flight.

“It could actually be to a passenger’s advantage to be able to point to a detailed set of rules rather than having to rely on an overzealous airline agent’s interpretation of a generalized clothing policy,” Yellin said.

But specific policies also add a layer of complexity to travel planning, Cronin said, and high-profile incidents like the one involving Kehidi and Hager could “expose airlines to reputational risks.”

“Should this trend persist, increased attention may be given to the issue of personal expression versus decency in the airline industry,” Cronin said.