wikipedia | A stand-your-ground law is a type of self-defense law that gives individuals the right to use reasonable force to defend themselves without any requirement to evade or retreat from a dangerous situation. It is law in certain jurisdictions within the United States. The basis may lie in either statutory law and or common law precedents. One key distinction is whether the concept only applies to defending a home or vehicle, or whether it applies to all lawfully occupied locations. Under these legal concepts, a person is justified in using deadly force in certain situations and the "stand your ground" law would be a defense or immunity to criminal charges and civil suit. The difference between immunity and a defense is that an immunity bars suit, charges, detention and arrest. A defense, such as an affirmative defense, permits a plaintiff or the state to seek civil damages or a criminal conviction but may offer mitigating circumstances that justify the accused's conduct.
More than half of the states in the United States have adopted the Castle doctrine, that a person has no duty to retreat when their home is attacked. Some states go a step further, removing the duty of retreat from other locations. "Stand Your Ground", "Line in the Sand" or "No Duty to Retreat" laws thus state that a person has no duty or other requirement to abandon a place in which he has a right to be, or to give up ground to an assailant. Under such laws, there is no duty to retreat from anywhere the defender may legally be. Other restrictions may still exist; such as when in public, a person must be carrying firearms in a legal manner, whether concealed or openly.
"Stand your ground" governs U.S. federal case law in which right of self-defense is asserted against a charge of criminal homicide. The Supreme Court of the United States ruled in Beard v. U.S. (158 U.S. 550 (1895)) that a man who was "on his premises" when he came under attack and "...did not provoke the assault, and had at the time reasonable grounds to believe, and in good faith believed, that the deceased intended to take his life, or do him great bodily harm...was not obliged to retreat, nor to consider whether he could safely retreat, but was entitled to stand his ground."