if you DO need paperwork, I'm sure it would be easy to find some licensed quack to put someone under his "care" and "prescribe" the need for a service or support animal. Heck you can just go buy a service dog vest off ebay and slap it on Fido and poof, a service dog.

But with all the news about knee defenders, it would be interesting to see what would happen if a big scary looking dog was there when the person refused to remove their knee defender...