Deadly force, also known as lethal force, is the use of force that is likely to cause serious bodily injury or death to another person. In most jurisdictions, the use of deadly force is justified only under conditions of extreme necessity as a last resort, when all lesser means have failed or cannot reasonably be employed. Firearms, bladed weapons, explosives, and vehicles are among those weapons the use of which is considered deadly force. The use of non-traditional weapons in an offensive manner, such as a baseball bat, sharp pencil, tire iron, or other, may also be considered deadly force. From Wikipedia
