Regulations issued in 1991 following the enactment of the Americans with Disabilities Act (ADA) required that public accommodations (which include restaurants, hotels, retail establishments, theaters and concert halls) modify their policies, practices, or procedures to permit the use of a service animal by an individual with a disability. Essentially this means that service animals accompanying persons with disabilities have to be admitted to establishments with policies otherwise excluding pets or other animals.

When the ADA was enacted, most service animals were "seeing-eye" dogs that assisted blind or sight-impaired persons. In most cases, these dogs were highly-trained and, because of their extensive training, were not likely to create a nuisance or a sanitary problem.

But over time, quite a variety of species came to be characterized by their owners as service animals including pigs, horses, monkeys, snakes, lizards, birds and rodents. Dogs and other animals that merely provide emotional comfort to their owners also have been characterized as service animals. The proliferation of creatures claimed to be service animals has posed obvious problems for many restaurants and hotels in terms of safety, sanitation and disturbance of other guests. Until now, however, proprietors were largely powerless to bar these types of animals from their establishments.