To use
deadly force is to attack a person with the sole intent to kill or injure said person, in other words, make the person
paralysed and incapable of attacking
you.
As defined by the
U.S. Congress, followed throughout the free world:
Use of Deadly Force:
The discharge of a firearm, other than a firearm loaded with less lethal munitions discharged by a peace officer (police, military) in the line of duty, in the direction of some person with the knowledge of the person's presence there, even though no intent to inflict serious physical injury can be shown. Also, The discharge of a firearm, other than a firearm loaded with less lethal munitions discharged by a peace officer in the line of duty, at a vehicle in which a person is known to be.