For example, if one man attacks another, the first one to use "deadly force" is in legal trouble. If someone attacks me with his fists, and I pull a knife or a gun and kill him, I'm going to have to have a damn good explanation for the judge, and I probably won't win.
HOWEVER, due to the strength discrepancy between men and women (it averages about 4 to 1), it's assumed that ANY attack on a woman by a man is a "deadly force" attack, and that she has a reasonable fear that he can kill her with his bare hands. Therefore a woman can pull a gun and shoot a man attacking her even if he doesn't have one, and it's simple self defense.
Hey, we GOT all this Common Law stuff from you guys, you know .... !