Well, this is more of a theory. I have not tested.....I HAVE NOT TESTED
This is my theory, I received a forum ban from the US forums so I changed to EU forums and I was able to post. If bans are regional MAYBE they are also regional in game. Meaning if you were banned while playing a US character you still may be able to play an EU character.
Like I said this is not tested, it works on forums however it needs to be tested in game. My account is not banned in game so I cannot test, if anyone else would like to test it would be great.
Also, if you botted or ect on both regions you might of been banned on both regions.