Timmy, a 13-year-old boy, has a father who is a violent alcoholic. One evening when Timmy's father has been heavily drinking, Timmy, his mother, and his father sit down to eat dinner at the living room table.

During that dinner, Timmy's father turns to his mother and states, "I thought I told you I don't like mashed potatoes you filthy woman! I'm sick of your cooking and your attitude. I'm going to choke the life out of you!"

Timmy's father grabs Timmy's mother and begins violently shaking and choking her. Timmy screams for his father to stop, but he doesn't listen. Timmy's mother's face begins to turn red and then purple as her eyes roll toward the top of her head. Timmy takes the carving knife from the kitchen table and stabs his father in the throat.

Clutching his throat, Timmy's father staggers from the table, bleeding internally and externally. Timmy's father collapses to the ground dead.

Timmy is charged with 1^st degree murder. What are the possible defenses?