The justification of self-defense generally allows the use of a reasonable amount of force when a victim of an attack has a reasonable belief that the use of force is necessary in order to prevent an imminent harm. For centuries, the justification of self-defense included a duty of the victim—or defendant—to retreat before resorting to force. Today in the United States, this duty has been eliminated entirely in many jurisdictions. In England, however, the duty has not been done away with but has, instead, been incorporated into the reasonableness aspect of self-defense, which evaluates whether the amount of force used by the defendant was reasonable and whether the defendant’s belief of an imminent harm was reasonable. The English version, therefore, allows the use of force even when retreat is possible but only when it can be shown that it was reasonable not to retreat. U.S. jurisdictions should undo the outright abandonment of the duty to retreat and adopt the English adjustment because it is better suited to both to gun culture in the United States and to the protection of human life.