“Is the dog a service animal required because of a disability?”
“What work or task has the dog been trained to perform?”
Those are the two questions that you can be legally asked to confirm the legitimacy of your service dog. They are also the questions I ask when I’m contacted by individuals who want me to train a service dog for them. Your service dog does not need to be certified by any organization. Your service dog does not need to wear an identifying vest. Your service dog does not even need to be professionally trained! Your service dog does need to be able to perform a specific task on your behalf - one that you can explain when asked.
Though professional training is not a requirement, you will want to ensure that your service dog, if you need one, is well-trained and fully housebroken, or it can be excluded from public places like any other dog. You must be able to control your service animal at all times, with or without a leash. The handler of a dog which is out of control may be legally ordered to leave a public space, if they cannot control their dog.
Emotional support, comfort, companion, or therapy dogs are not considered service animals under the ADA (Americans with Disabilities Act) and are not entitled to the same freedoms as service dogs. People frequently contact me and ask if I can train their dog to be a service dog. But the real question should be “Will you help me train my dog to do (TASK) in order to help me with (DISABILITY).”
I am not a lawyer, and this page should not be considered legal advice. For more information on what constitutes a service animal, please follow up with the sources below.