Several major U.S. airlines are challenging a new federal rule aimed at improving travel for those with disabilities.

American Airlines, Delta Air Lines, JetBlue, Southwest Airlines, United Airlines and their trade association, Airlines for America, or A4A, are petitioning the U.S. Court of Appeals for the Fifth Circuit to review the regulations, which the Department of Transportation finalized in December.

The rule, which was hailed by the Biden administration as the largest expansion of rights for airline passengers with disabilities in a generation, requires annual training for airline staff and contractors who help people with disabilities or who handle wheelchairs. It also sets out stronger standards for how this type of assistance is provided, clarifying that it must be “safe and dignified,” and spells out what airlines must do if a wheelchair is damaged or delayed.

Notably, the regulation makes it an automatic violation of the Air Carrier Access Act if airlines damage or delay the return of a wheelchair or another assistive device.

The airlines are now arguing that the Transportation Department overstepped.

“As the airlines will explain, the court should ‘hold unlawful and set aside’ the rule, in whole or in part, because provisions of the rule exceed DOT’s statutory authority and the rule violates the Administrative Procedures Act,” reads the petition to the court, which goes on to describe the rule as “unlawful.”

Despite these claims, those behind the legal action indicated that they do not oppose the whole rule, just certain provisions.

“U.S. airlines are dedicated to providing exceptional customer service and ensuring a safe, inclusive travel experience for passengers with disabilities,” said Hannah Walden, director of communications at Airlines for America. “A4A and our passenger carriers are continuously engaged with the disability community, the Department of Transportation (DOT) and others to identify and implement solutions to accessibility barriers.”

When the rule was finalized late last year, the Transportation Department noted that about 5.5 million Americans use wheelchairs and that 1 out of every 100 wheelchairs or scooters on domestic flights is damaged, delayed or lost.

The new rule took effect Jan. 16, but the Trump administration said this week that it will delay enforcement until March 20 “to review the final rule to ensure that it is consistent with the law and administration policies.”

The Transportation Department did not respond to a request for comment about the rule and the airlines’ legal action.