Typically that defense only holds water when two entities are in totally separate domains and even then you would probably still have to go to court to defend yourself.  (Apple Corps v. Apple Computer is a notable example)<p>In this specific case I doubt you could make the argument that the two things are in separate domains and unlikely to be confused. Lego has sold programmable Lego sets since 1987 and even had their own programming language &quot;Lego TC Logo&quot;.  Present day they still sell programmable Lego sets under the Lego Mindstorms NXT brand.