A service dog performs a job like pulling a wheelchair, pushing an elevator button and getting a cell phone for the owner.

The Americans with Disabilities Act (ADA) explains: "A service animal means any dog that is individually trained to do work or perform tasks for the benefit of an individual with a disability, including a physical, sensory, psychiatric, intellectual, or other mental disability."

RELATED: How fake service dogs harm real ones

Although vests help define the dog's role, federal law does not require service dogs to wear one, according to Rebecca Wisch, Associate Editor of Animal Legal & Historical Center at Michigan State University College of Law. 

Facts about fake service dogs

Virginia and 18 states have misdemeanor penalties for individuals who falsely claim a pet as a service dog.
However, DC and Maryland do not have Fraudulent Representation of Service Animal laws.

Look up each state law on fraudulent service dogs.

When encountering a dog and its owner 
- Is this animal required because of a disability? (yes or no) 
- What job does the dog perform for you?
You CANNOT ask: 
- What is the person's specific disability?
- Can I see the animal demonstrate the trained task(s)?
- Can I see documentation to prove the dog is a service animal? 
ADA laws DO apply to the following trained dogs who need to be with their owners when traveling: 
Hearing Dogs
Seeing-eye Dogs
Service Dogs
ADA laws DO NOT apply to the following dogs, so they may be banned from a specific area: 
Comfort dogs
Emotional support dogs
Therapy Dogs
A service dog CANNOT be removed from the immediate premises just because a nearby person(s) is allergic to dogs or afraid of dogs. 
A service dog CAN be removed if: 

The dog is NOT housebroken.  
The owner does NOT have control of the dog (leashed/tethered or under verbal command at all times).  

See more service animal laws: