It is the Castle Doctrine. If you are somewhere that you have the legal right to be and are confronted, you have no legal duty to retreat. You have the right to remain and use deadly force to protect yourself and others from deadly force or significant bodily injury. I belive that most states are going to this legislation and every state that it passes in is just a little step further into 2A rights being taken as seriously as they were intended.
ΜΟΛΩΝ ΛΑΒΕ- Greek:"Come and take them..." Meaning: Here we peaceably stand as armed and free men, willing to defend that peace, and ready to make war upon anyone who threatens that freedom.