The general rule on self-defense is that the defendant must have had a reasonable fear of imminent harm, and they must have used a reasonable amount of force, which must have been proportionate to the force being used against them. (Read more here about the requirements of self-defense.) However, there are also situations in which the defendant acts on an unreasonable fear of imminent harm or in which the defendant uses an unreasonable amount of force. This is known as imperfect self-defense. It cannot defeat a charge entirely, but it may allow a defendant to reduce the level of the charge and the associated penalties.
Imperfect self-defense usually applies only in the context of homicide or attempted homicide. When a defendant is charged with murder, the charge may be reduced to manslaughter on the basis of imperfect self-defense. The idea is that, while the defendant’s actions were unjustified, they did not have the malice element that is required to get a murder conviction. This could mean that the defendant will not face the death penalty or life in prison. Not every state applies a rule of imperfect self-defense, and its details vary depending on the state. Imperfect self-defense generally does not apply to other crimes that include a malice element.
Proving Imperfect Self-Defense
This defense contains most of the same elements as ordinary self-defense. In other words, the defendant needs to show that they actually believed that they were facing an imminent threat of death or serious bodily harm. Since this defense arises in the homicide context, they need to show that they believed not only that the use of force was necessary but also that they needed to use deadly force to prevent the harm.
Ordinary self-defense requires the defendant to meet both a subjective standard and an objective standard, but imperfect self-defense only requires the defendant to meet a subjective standard. Their actions will not be compared to a reasonable person. However, a defense often raises both types of self-defense arguments, and the jury will need to decide whether they meet the objective standard. If they do not, but the jury believes their testimony or other evidence, the jury still may find that they meet the subjective standard. Sometimes these issues can be resolved in the plea bargaining process as well, when the prosecutor agrees to reduce a charge from murder to manslaughter if there is some evidence for imperfect self-defense.
Imperfect self-defense may not be the only available defense in some homicide cases. State laws may provide stronger defenses, such as the stand your ground defense or the castle doctrine. A defendant can raise all of the possible defenses that may apply.
Additional Applications of Imperfect Self-Defense
A defendant sometimes can use an argument of imperfect self-defense in a broader range of situations related to a homicide charge. A state may permit this defense if the defendant provoked the interaction but then faced an unreasonable use of force by the victim, to which they responded with reasonable force. If a state imposes a duty to retreat before using force, a defendant who otherwise might have a perfect self-defense argument but failed to retreat might be able to use an imperfect self-defense argument. A history of violence perpetrated by the victim against the defendant, such as abuse in a domestic relationship, may justify an imperfect (or even perfect) self-defense argument if the specific interaction that resulted in the charge did not justify using deadly force.