Self Defense - The Act of Protecting One's Self

Self defense is the act of protecting one's self against physical force or the immediate threat of force. It can justify conduct which would otherwise give rise to criminal or civil liability. It can operate as a defense to virtually any criminal or civil wrong which involves the use or threat of physical force, such as assault, battery, and homicide.

To successfully argue self defense in a trial for homicide, the defendant must show that he or she acted with a genuine belief that they were in danger of death or severe bodily harm, that their conduct was necessary to prevent that harm, and that a reasonable person in the same situation would have had the same belief, and acted in a similar manner.

There are 2 basic types of self defense in a murder trial: perfect and imperfect. Self defense is perfect when the actor truly believed that they were in danger of death or grave bodily harm and that belief was reasonable. This requires the court to look at the defendant's mental state (did they honestly believe that they were in danger?) and the surrounding circumstances (given the facts, was that belief reasonable?).

For example, suppose Al pulls out a gun and begins firing into a crowd. Bob, who happened to be in the line of fire, pulls out his own gun and shoots Al, killing him. Bob has acted in perfect self defense: he truly believed that he was threatened with death or severe bodily harm, and that belief was reasonable under the circumstances (he was being shot at, after all). If Bob were charged with murder, and he successfully proved the above facts, he would be completely exonerated.

Imperfect self defense is when a person acts with an honest belief that they are in immediate danger of death or severe bodily injury, but, given the facts, that belief was not reasonable. This does not completely exonerate the defendant, but if it is shown, it can reduce first-degree murder to voluntary manslaughter, a less severe crime.

Changing the above example slightly, suppose that Al pulls out a water pistol, and begins shooting it into the crowd. Bob honestly believes that the water pistol is filled with poison, and anybody who is sprayed with it will die, but he has no reasonable basis for this belief - he's just paranoid. Acting on this belief, he shoots and kills Al. If Bob is charged with murder, he will be able to argue imperfect self defense, and if he proves the facts as stated above, he will not be convicted of first-degree murder, but of voluntary manslaughter.

To successfully prove self defense, one must also show that the amount of force they used was reasonable. Lethal force is only reasonable when the actor is threatened with death or severe bodily harm. If lesser harm is threatened, less force is justified. So, if Al runs toward Bob screaming that he's going to beat Bob up, but there is no indication that he is going to try to kill Bob, Bob may only repel Al's attack with the minimum amount of force necessary to protect himself, and no more. In such a case, Bob would probably not be justified in shooting Al, but he would be justified in using pepper spray to incapacitate him while he escapes, or using some other non-lethal force to defend himself.

In many states, a person must first attempt to escape the danger before resorting to physical force. This adds another requirement for a successful showing of self defense: escape was impossible. Some states, however, allow a person to stand his or her ground.

In the majority of states that require a person to first attempt to escape, there is an exception for a person who is attacked in his or her own home. Known as the "castle doctrine" (based on the idea that one's home is his castle, and he should not be required to retreat from it, rather than defend it). However, the other rules associated with self defense are basically the same when it occurs in the actor's own home: there must be an honest and reasonable belief about a threat of serious harm.