From last year's post about the "Emotional Support Animal" scam:
The larger story is that a very poorly drafted regulation was written for airplane passengers. That loophole has been ripped wide by pushy, self-centered people telling lies and making extreme right claims bolstered by fake paper and store-bought decals. Toss in general ignorance on the part of poorly trained clerks facing a problem for the first time, natural confrontation avoidance, and a generalized fear of getting sued by lawyers, and you have biting dogs, kicking alpacas, disease-spreading turtles, and defecating pigs in public spaces.
The poorly written regulation that started it all off was cranked out in June 2004 by some idiot at the FAA who no doubt meant well. In their “guidance about unusual service animals” the FAA notes that "service animals" were initially meant to be guide dogs for the blind. Those animals have been permitted on commercial airlines since at least 1977 and because they are well-trained and with sensible owners who are also well-trained, they have presented virtually no problems at all.
The wrinkle is that sometime around 2003, someone at the Department of Transportation decided it was OK to expand the definition of a service animal to include "an animal used for emotional support". And an "emotional support" animal, the DOT decided, did not need to have any training at all.