A service dog may generally accompany his disabled handler any where in a public accommodation where the public are permitted with certain exceptions. The service animal may be excluded if it poses a direct threat or fundamental alteration of the services offered by the public accommodation.
For example, on a case-by-case basis a ambulance crew may decide not to permit a service animal in the treatment area of an ambulance if lack of space means the dog would interfere with the necessary movement of personnel providing emergency care. That might be a "fundamental alteration" if the presence of the dog prevents the emergency workers from performing their jobs.
A service animal might be excluded from an area that requires special clothing, such as a hospital ICU (Intensive Care Unit), or a computer "clean room," where the tiniest particle can ruin the manufacture of computer chips. A service animal might be excluded from an area where zoo exhibits can come in direct contact with human visitors, such as an aviary. On a case-by-case basis, a service animal might be removed if its presence is frightening a zoo exhibit to the point of harming the exhibit.
Service animals may also be excluded from places that are not public accommodations, including but not limited to worship services of a church, private clubs, some Native American facilities, and military bases.
The exceptions are few, but they do exist. The keys in evaluating whether a service animal should be permitted in a given area are:
1. Would the presence of this specific animal pose a direct (known and not just hypothesized) threat in this specific instance, not based on past experiences with other service animals or dogs in general?
2. Would the presence of this specific animal fundamentally alter the goods or services provided by the public accommodation?
3. Is there some reasonable accommodation possible? Reasonable accommodation is the art of compromise. Is there is a readily achievable solution which permits the person with a disability to access goods and services, and which does not constitute an undue hardship on the business?