At least here in Ontario you are issued a photo ID with both the dog and the client pictured on it. If you can't produce it then you don't have a right to be anywhere a normal dog can't go. We keep ours in a pocket on our dog's vest so it is always present. I've never been asked to produce it either and I've only ever been challenged once. In that case it was a small country business who understood once the rules were explained.
A service dog has the right to go anywhere except a food prep area and an area in which high levels of hygiene are required (an operating room for example).
Just to be clear my son's service dog is an Autism Service dog and is fully certified via
http://www.dogguides.com/about.html