Unit 32: Self-Defense I


  • Dressler 211-225 (stop before 18.05)

  • Goetz (CP)

Key Terms: 

  • necessity

  • proportionality

  • deadly force

  • aggressor

  • duty to retreat

  • stand your ground laws

  • castle doctrine

  • imperfect self-defense


At common law, a non-aggressor is legally permitted to use force in self-defense if she reasonably believes the use of force is necessary to prevent the imminent use of unlawful force by another person against her or an innocent third party. The burden is on the defendant to introduce and argue a self-defense claim, though the ultimate burden remains on the prosecutor to prove the defendant’s guilt beyond a reasonable doubt.

There are three core requirements for a successful self-defense claim. (These requirements also apply to a defense-of-others claim.)

First, the use of force is only permissible if, and to the extent that, it is necessary. Force is not allowed if the non-aggressor can safely avoid harm through non-violent means. This means that even if the non-aggressor reasonably fears the use of deadly force, he is not justified in using deadly force if a lesser degree of force would suffice.

Second, the use of force in self-defense must be proportional to the perceived imminent harm. When a non-aggressor uses deadly force in self-defense, she must reasonably believe it was necessary in order to prevent the imminent use of deadly force.

Finally, the use of force must be motivated by a reasonable belief that the use of unlawful force was imminent. Reasonable belief has two components: (1) the non-aggressor must actually believe that unlawful force was imminent, and (2) the belief must be objectively reasonable. It is not necessary that the non-aggressor be correct in her belief, as long as the belief itself was reasonable.

An aggressor (generally defined as someone one who initiates or provokes the use of force) is not entitled to a self-defense claim. The use of certain language, even without physical action, can qualify an individual as an aggressor. What language counts is context-specific and not always obvious, however. For instance, if Sally uses threatening language that creates a reasonable fear in Bill that she is about to use imminent force against him, Sally might be the aggressor even if Bill is the first to use physical force. However, Sally would not be the aggressor if, for instance, Sally’s insulting of Bill’s favorite movie incites Bill to violence.

An initial aggressor can regain access to a self-defense claim if he withdraws from the conflict, and effectively communicates this withdrawal to the initially intended victim. The communication can be express or implicit (such as if the aggressor throws down his weapon and runs away). Additionally, some jurisdictions allow a non-deadly aggressor to make a partial self-defense claim if the non-aggressor escalates the conflict. For example, if Jim punches Fred and Fred responds by pulling a gun, Jim might be legally permitted to use force against Fred in self-defense, even though he could still be prosecuted for battery for the initial punch.

Some jurisdictions recognize imperfect self-defense, which reduces the grading of a crime but does not eliminate criminal culpability.  For example, if Erin unreasonably believes that the use of deadly force is necessary to prevent the imminent use of unlawful force against her, her crime might in some jurisdictions be graded as manslaughter rather than murder.

Traditionally, there was a requirement that an individual faced with the threat of imminent harm was not justified in using force in self-defense if he could safely flee from the conflict and was aware of that possibility. This limitation makes sense, because the use of force isn’t strictly necessary if a safe, non-violent escape route is available. However, “stand your ground” laws, which impose no duty to flee, are becoming increasingly common, and now appear in some variation in a majority of states.  (Florida’s law, which is at issue in the death of Trayvon Martin, is among the most controversial).

Under what is known as the “castle doctrine,” some jurisdictions that retain a duty to retreat do not extend that duty to aggression that occurs in the non-aggressor’s home.  Some of these jurisdictions make an exception to the castle doctrine in cases involving an aggressor and non-aggressor who live in the same home.

Questions For Review:

Q1: Do you agree with “stand your ground” laws, or do you think they should be abolished? What arguments support your position?  What arguments challenge your position?

Q2: Some people have criticized the “imminence” requirement as unnecessarily restrictive. Do you agree with an imminence requirement? Should it be limited in some way?

Q3: Evelyn and Arthur meet each other in a bar, and quickly get into a heated argument. Arthur says, “Too bad you’re a girl, otherwise I’d kick your ass,” to which Evelyn responds by punching Arthur in the face. Arthur reaches into his pocket for something that looks to Evelyn like a gun. Evelyn quickly pulls out a knife and stabs Arthur, killing him. As it turns out, Arthur was actually reaching for his cell phone to call the police, but Evelyn later told investigators that the lighting at the bar made his cell phone case look like a gun. Evelyn is charged with murder, and claims that she acted in self-defense. Is she entitled to a self-defense claim?