OldMarksman, I am not a lawyer. However, I have been told by former prosecutors and defense experts that the alleged perpetrator's background can be brought up in almost any jurisdiction, as it pertains to past patterns of behavior and their relevance to the behavior the shooter/defender claims to have seen evinced.
In other words, if a BG has a prior history of using a crowbar to threaten and then attack people as they get out of their car, in their driveway, and if the client claims that the BG threatened him with a crowbar as he was getting out of his car, then the odds are good that past history will be allowed, at least as it relates to that specific MO.
OTOH, the simple fact of the BG's prior history is otherwise irrelevant, unless the client can prove they had prior knowledge of that history.
Example, a woman knows that a particular man in her neighborhood has previously been convicted of rape or sexual assault. If she can establish that she knew that prior to her encounter with the man, then his history (or what she knew of his history) would be relevant.
Frank Ettin or Spats, please feel free to correct me.