The early August determination by the DOT that it will continue requiring airlines to allow passengers to bring emotional support animals (ESAs) on planes won't be the last word on the contentious issue.

Last week, the trade group Airlines for America (A4A) renewed its call for the DOT to adopt the definition of a service animal shared by the Department of Justice and the Americans With Disabilities Act, which includes no provision for ESAs.

There's reason for A4A to be optimistic. The DOT has already said it intends to issue a proposed rule relating to service animals on aircraft, including ESAs, before the year is out. Just last week, in fact, the department sent a draft of the proposed regulation to the Office of Management and Budget for feedback.

Meanwhile, other efforts, some in state legislatures, are geared toward reining in abuse of ESA regulations, especially in the long-term housing sector, where their acceptance is also required by law.

"I believe the concept of an ESA is a well-intended, valuable concept that has now developed into something that is frequently nonsensical," said Jeffrey Younggren, a clinical professor in the University of New Mexico's department of psychiatry and behavioral sciences.

Younggren's third co-authored paper on the subject was published this month in the American Psychological Association journal.

In its Aug. 8 Final Statement of Enforcement Policies Regarding Service Animals on Flights, the DOT stated that it will direct enforcement efforts toward ensuring that airlines allow passengers to travel with one dog, cat or miniature horse for emotional support, if needed.

The department also stated that airlines cannot forbid specific dog breeds from being used as ESAs, contravening Delta's June 2018 ban of pit bulls in that role.

Airlines can, however, require flyers to submit documentation 48 hours before a flight from a mental health professional attesting that they have an emotional disorder and that they would be helped by an ESA. Airlines began implementing such requirements in March 2018.

The final statement, however, is only the DOT's final stance on regulations currently on the books. The new rule-making proposal that the DOT is working on will likely alter the regulations, though it's not yet clear in what way or how significantly.

A simple web search reveals that provisions allowing for emotional support animals on aircraft are being abused by flyers.

Numerous online businesses offer to provide ESA validation letters from mental health clinicians with same-day delivery, often after only a short online mental health assessment. Some of those businesses aren't even subtle about the fact that they are helping clients avoid carry-on pet fees, which typically cost $125 one-way.

For example, the Waggy.pet website states, "An ESA letter from a licensed therapist is all you need to gain legal access to airline cabins and pet-restricted housing without fees and deposits."

The company offers a single ESA travel letter for $49 as well as package deals for additional letters.

In a few highly publicized cases, the exploitation of emotional support animal regulations has reached the point of absurdity. Last summer, an ESA on United flew with its own ESA, CEO Oscar Munoz told Bloomberg at the time.

At other times, improperly trained ESAs have proven to be a danger. In July, for example, an emotional support dog bit an American Airlines flight attendant, who required five stitches.

The number of passengers bringing ESAs aboard U.S. airlines in recent years has grown at a far faster rate than the number of passenger enplanements. According to A4A, in 2017 888,000 people flew with ESAs, up 58.3% year-over-year. In that same period, passenger enplanements increased just 3.1%.

Last year, as airlines implemented tougher documentation requirements, the growth in boarding ESAs slowed to 14.3%, which was still three times the 4.7% growth in passenger enplanements.

Sharon Pinkerton, A4A's senior vice president for policy, said that checking the validity of ESA documentation is difficult for airlines.

"That's not really our area of expertise, which is why we continue to make the call to use the ADA definition, because of the abuse that's out there," she said.

As airlines, flyers and the mental health and disability communities await the new DOT regulatory proposal on ESAs, at least two state legislatures have considered but thus far failed to pass their own ESA-related legislation.

A North Carolina bill passed this year by the state's House of Representatives was geared primarily toward ESA fraud in the housing sector. It would have made it a misdemeanor to misrepresent a need for an emotional support animal to a landlord. A similar bill was introduced in the Florida Senate this year, but also died.

One proponent of that Florida bill was Chaz Stevens, CEO of Boca Raton-based ESAD, which provides emotional support letters through a network of mental health clinicians around the country. Unlike many online ESA letter services, ESAD requires clients to sit for a 45-minute assessment with one of its clinicians. The charge for the service is $240, Stevens said.

"There are folks who come to us and say, 'I don't want to check my dog into cargo, I don't way to pay the fees,'" he said. "There is a level of fraudulent interest. We say, 'Have a good day.'"

Still, Stevens said that between 90% and 99% of ESAD's clients are issued the ESA letters they are seeking.

In Younggren's recent paper, he and his co-authors pointed out that there remain no clear regulatory guidelines for conducting ESA assessments. They proposed a four-part certification process that starts with the clinician demonstrating a proper understanding of the laws regulating ESAs. After that, the client requesting the letter would undergo a thorough assessment for determination of a disability and a related need.

Next, the animal in question would be assessed to ensure it can fulfill the functions of an ESA. Finally, a clinician would assess the interaction between the patient and the animal to determine if the animal's presence would be demonstrably beneficial to the patient.

"We really need to get this defined," Younggren said. "We need to get this back in the realm of reasonable."