Affirmative Defense for Mountain Murders

So, I'm having a discussion with another attorney today and he was trying to explain how mountain folk feel about murder. As he explained it there is a two part affirmative defense which doesn't exist in other parts of the Commonwealth:

(1) That sonuvab!tch needed to get kilt, and
(2) I was the right person to do it.

We discussed for a while whether this is a perfect defense and came to the conclusion that it is in some cases, but not in others. It seems to depend on how much a sonuvab!cth he is and whether he is either (a) on your land, or (b) with your wife.