Hi, I found this thread via a Google Alert (e-mail for the search term "service dog") and would love to help you out! I'm disabled and have a service dog, so I know the laws well.
You are correct that therapy dogs are not service dogs. You are correct that therapy dogs do not have any type of legal public access. They are pets through and through. The "therapy dog" designation is just so hospitals and such know that the dog has been trained to meet certain requirements before they choose to invite the dog into the building. The therapy dog does not otherwise have access to the building; they must be invited.
You are also correct that emotional support dogs are not service dogs. You are correct that emotional support dogs do not have any type of legal public access. They are pets that a doctor has prescribed for a person who has a mental disability. The pet helps the person emotionally by its presence, being cared for, cuddling, etc. - by just being a dog. It is not trained to help the person in any way.
There are service dogs for people with mental disabilities - these are called psychiatric service dogs, not psychotic service dogs.
These dogs are trained to do tasks that mitigate the person's actual mental disability. The problem is, a lot of people try to cheat the system by saying their mental conditon is a disability when it isn't and/or by saying their dog is a psychiatric service dog for them when the dog does not do any tasks or the things the dogs have been trained to do don't mitigate the person's disability (i.e. the dog can retrieve items, but the person does not have any difficulty getting items themselves; the dog carries medications in a pack on its back, but the person is able to carry medications in their pocket, purse, or other bag).
A service dog is a dog that has been individually trained to do work or perform tasks for the benefit of an individual with a disability. A disability is a physical or mental impairment that substantially limits one or more major life activities (examples of which are seeing, hearing, walking, caring for self, etc.).
Businesses are allowed to ask three questions:
1. Are you disabled? (Yes or no answer; you cannot ask what their particular disability is.)
2. Is this your service animal?
3. What tasks has your service animal been trained to do that mitigate your disability? (The person must name at least one trained task their dog does that mitigates their disability.)
A business cannot demand to see certification, ID, paperwork, prescription, etc.
Even though most people say "service dog/animal access", it is actually the person who has access, not the dog. The person is able to bring the service dog with them under the law because the service dog is legally a medical device (like a wheelchair or cane), not a pet. The law is a person cannot be denied access because of their disability. If somebody denies access to a person because they use a service animal (or because they use a wheelchair or because they use a cane), they are denying a person access because of their disability and that is against the law.
There is no set $25K fine for denying a disabled person access, so it sounds like this lady is money-hungry or just trying to scare you into letting her bring her pet with her. The ADA is a civil rights law, not a criminal law; the point of a lawsuit is access, not money, but not everybody realizes that. Nor do they realize all the proof they will need for a lawsuit (proof they are disabled, proof the dog is trained to do tasks that directly mitigate their disability, and proof they were excluded because of their disability and not for another reason such as their attitude or smell/uncleanliness/etc.).
Besides asking the questions, you can observe the animals' behavior. If the animal is at the person's side (or slightly ahead, for animals that guide or pull for tasks) except when doing a task (such as retrieving an item), the animal is obedient, the animal is under control, and the animal otherwise acts "invisible", there is a good chance it is a service animal. If the animal is misbehaving, breaking items, causing accidents, barking, or otherwise being a nuisance, it is likely to be a pet. Even if a real service animal is disruptive (such as barks repeatedly during a movie, breaks an item, or otherwise is not under control), you can legally exclude them.
As for your particular situation, under the federal laws, you should exclude this lady's dog from your business. A therapy dog has no place or legal standing in your business, nor does an emotional support dog. A service dog must have been trained to do tasks that mitigate the person's disability, which the lady is not answering that her dog does any such thing, so she cannot bring her dog in.
Before you do anything, however, DO check your state's laws; I have heard rumors that Utah wanted to pass a law giving emotional support animals access to public places. I don't know if that law was ever passed or what the specifics of it are. You should be able to find the law on your state's Web site or at your library. (For all Utah businesses' sakes, I hope the law was not passed!)
I hope this helps!
You are correct that therapy dogs are not service dogs. You are correct that therapy dogs do not have any type of legal public access. They are pets through and through. The "therapy dog" designation is just so hospitals and such know that the dog has been trained to meet certain requirements before they choose to invite the dog into the building. The therapy dog does not otherwise have access to the building; they must be invited.
You are also correct that emotional support dogs are not service dogs. You are correct that emotional support dogs do not have any type of legal public access. They are pets that a doctor has prescribed for a person who has a mental disability. The pet helps the person emotionally by its presence, being cared for, cuddling, etc. - by just being a dog. It is not trained to help the person in any way.
There are service dogs for people with mental disabilities - these are called psychiatric service dogs, not psychotic service dogs.

A service dog is a dog that has been individually trained to do work or perform tasks for the benefit of an individual with a disability. A disability is a physical or mental impairment that substantially limits one or more major life activities (examples of which are seeing, hearing, walking, caring for self, etc.).
Businesses are allowed to ask three questions:
1. Are you disabled? (Yes or no answer; you cannot ask what their particular disability is.)
2. Is this your service animal?
3. What tasks has your service animal been trained to do that mitigate your disability? (The person must name at least one trained task their dog does that mitigates their disability.)
A business cannot demand to see certification, ID, paperwork, prescription, etc.
Even though most people say "service dog/animal access", it is actually the person who has access, not the dog. The person is able to bring the service dog with them under the law because the service dog is legally a medical device (like a wheelchair or cane), not a pet. The law is a person cannot be denied access because of their disability. If somebody denies access to a person because they use a service animal (or because they use a wheelchair or because they use a cane), they are denying a person access because of their disability and that is against the law.
There is no set $25K fine for denying a disabled person access, so it sounds like this lady is money-hungry or just trying to scare you into letting her bring her pet with her. The ADA is a civil rights law, not a criminal law; the point of a lawsuit is access, not money, but not everybody realizes that. Nor do they realize all the proof they will need for a lawsuit (proof they are disabled, proof the dog is trained to do tasks that directly mitigate their disability, and proof they were excluded because of their disability and not for another reason such as their attitude or smell/uncleanliness/etc.).
Besides asking the questions, you can observe the animals' behavior. If the animal is at the person's side (or slightly ahead, for animals that guide or pull for tasks) except when doing a task (such as retrieving an item), the animal is obedient, the animal is under control, and the animal otherwise acts "invisible", there is a good chance it is a service animal. If the animal is misbehaving, breaking items, causing accidents, barking, or otherwise being a nuisance, it is likely to be a pet. Even if a real service animal is disruptive (such as barks repeatedly during a movie, breaks an item, or otherwise is not under control), you can legally exclude them.
As for your particular situation, under the federal laws, you should exclude this lady's dog from your business. A therapy dog has no place or legal standing in your business, nor does an emotional support dog. A service dog must have been trained to do tasks that mitigate the person's disability, which the lady is not answering that her dog does any such thing, so she cannot bring her dog in.
Before you do anything, however, DO check your state's laws; I have heard rumors that Utah wanted to pass a law giving emotional support animals access to public places. I don't know if that law was ever passed or what the specifics of it are. You should be able to find the law on your state's Web site or at your library. (For all Utah businesses' sakes, I hope the law was not passed!)
I hope this helps!
