But, Illegal Burgers (<- plural) in Fremont, A is NOT the same company as WCVC's "Illegal Burger."
The guy who owns it was once affiliated with WCVC (in a now defunct CA branch of WCVC), but now, except for the closeness of the name, and the similarity of some of the menu items, it is an independent company that is NOT an Illegal Burger franchise.
I don't know how they have gotten away with the name similarity, EXCEPT, perhaps, that they have not tried to trademark the name. If trademarks are not involved, two companies in different states may have the same name (perhaps with some limitations).
