The U.S. Department of Transportation (DOT) has ruled that emotional support animals will no longer be considered service animals on flights in an update to a rule that has become highly controversial.

The DOT released a statement announcing this on Wednesday, adding that they had received over 15,000 comments on the proposal, which was pitched in January, before revising the Air Carrier Access Act.

“The final rule announced today addresses concerns raised by individuals with disabilities, airlines, flight attendants, airports, other aviation transportation stakeholders, and other members of the public, regarding service animals on aircraft,” the statement said.

The DOT added that going forward, a service animal will be defined as “a dog that is individually trained to do work or perform tasks for the benefit of a person with a disability.”

Fox News reported that “moving forward, the department is allowing airlines to require DOT-approved forms affirming a service animal’s health, behavior and training before travel, and allowing carriers to cap the number of service animals traveling with a single passenger at two.”

“In addition, the DOT has given airlines the OK to require a service animal to fit within its handler’s foot space on the airplane, and mandate that the animal be harnessed, leashed, or tethered at all times on the plane and within the airport during the travel journey,” Fox added.

Though the DOT is allowing airlines to refuse transport to service animals acting aggressively, they can’t refuse to transport a service animal based on breed.

The topic of emotional support animals traveling has been a controversial one since 2018, when an emotional support peacock named Dexter and his owner were not permitted to board a United Airlines flight. Just a few months later, a French bulldog died on a United Airlines airplane after a flight attendant accidentally put it in an overhead bin for the entirety of the trip.

Emotional support airlines have routinely been in the headlines ever since, with some saying that they should be allowed to fly while others have passionately argued that they do not belong on airplanes. This announcement by the DOT will hopefully put this debate to rest in the future.