Research done: Google terms: maryland law self defense; Wikipedia articles: "Right of self-defense", "Self-defense (United States)", "Right of self-defense in Maryland".
The situation is as follows:
An 18-year-old girl is left at charge in home while her parents go out (we'll call her Emily). Her three siblings are in the house: two girls (ages 16 and 14), and one boy (age 12). The parents are out all weekend.
The 14-year-old (we'll call her Mary) had up until recently been dating the captain of the football team, an 18-year-old (called Frank). They broke up for a variety of unimportant reasons. Anyway, one night, during the period while the parents were away, Frank breaks into the house and confronts Mary. They argue, and then Frank attacks Mary.
The layout of the house is such that no-one hears the commotion. The brother's bedroom is on the downstairs floor, Mary's is on the second floor, and her two sisters sleep in an attic bedroom. Anyway, Emily thinks she hears something, so she goes downstairs to check to make sure everything is all right. She finds Frank in the middle of the process of raping Mary. She attacks Frank, knocking him off of her sister. He stumbles back and runs out of the room, and she goes after him, grabbing a lamp off the bedside table and swinging it like a baseball bat. She manages to hit him on the head, and Frank dies.
My question is as follows: Would Emily be charged with a crime? Could she successfully claim self-defense?
From my research, I've ascertained that Emily has the right to defend her sister (defense of others). According to the Maryland Criminal Pattern Jury Instructions (MPJI-Cr 5:01), her initial attack, where she gets Frank away from her sister, satisfies the requirement that "The defendant actually believed that the person defended was in immediate and imminent danger of bodily harm."
Afterwards, however, I'm not so sure. When she hits Frank on the head, he is in retreat; she and her sister are no longer in danger. (I'm pretty sure it violates MPJI-Cr 5:01: "The defendant used no more force than was reasonably necessary to defend the person....") I'm sure she could claim extreme emotional disturbance as well.
I also considered the castle doctrine, which I found in some statutory law from 2007, but am still unsure if it were to apply. From what I understand, castle doctrine allows you to stand your ground (and not be forced to retreat) within your own home, but I'm not sure it applies here.
In light of the initial crime -- Frank raping Mary -- would charges be brought against Emily at all?
EDIT: sorry! hit "submit" too soon.