Service Animals have been an accepted part of our society for a long time.  Dogs have been used in America since at least the late 1920's to assist persons with disabilities.  Most businesses post signs that state that 'service animals are welcome', or something to the effect.  According to the American's with Disabilities Act (ADA):

Establishments that sell or prepare food must allow service animals in public areas even if state or local health codes prohibit animals on the premises.

But not all businesses are so quick to comply with the ADA requirements.  Earlier this month, Richard Hunter, a US Army veteran, went out to lunch with his son and a co-worker at a Subway restaurant in Newark, NJ and was promptly tossed out because of his service dog.  ABC News 7, Newark, has the complete story in the video below.