⚡ 10-Second Rule
You may use the amount of force you reasonably believe you need, right now, to stop an unlawful attack.
🧒 ELI-10 Scene
At recess, Leo shoves Ben into the fence and cocks his fist again. Ben pushes Leo back, hard, and Leo falls. The playground monitor doesn't punish Ben. He matched a shove with a push, right when it was needed. Now imagine Ben instead grabbed a baseball bat and swung at Leo's head. Everyone's reaction changes instantly. The answer to a shove is a push, not a bat. That matching instinct is the whole doctrine.
⚖️ Actual Rule
A person may use nondeadly force when she reasonably believes it is necessary to protect against imminent unlawful force. Deadly force is permitted only when she reasonably believes she faces an imminent threat of death or serious bodily injury. Under the majority rule, there is no duty to retreat before using deadly force; a minority of states require retreat when it can be done in complete safety, except inside one's own home (the castle doctrine). [NJ-VARIANT: flagged for future Eli Explains NJ Law module] As Justice Holmes wrote in Brown v. United States, 256 U.S. 335 (1921), "Detached reflection cannot be demanded in the presence of an uplifted knife." An initial aggressor loses the defense unless (1) she withdraws from the encounter and effectively communicates that withdrawal, or (2) the victim suddenly escalates a nondeadly fight into a deadly one. Defense of others permits force the defender reasonably believes the third person would be entitled to use in self-defense (majority: reasonable appearance controls, even if mistaken). Defense of property permits only reasonable nondeadly force; deadly force is never permitted solely to protect property, including by mechanical devices such as spring guns. An honest but unreasonable belief in the need for deadly force is not a complete defense; in many states it mitigates murder to voluntary manslaughter — imperfect self-defense, covered in the homicide lessons.
ELI-10 translation: match the force to the threat, and only a truly deadly threat unlocks deadly force back.
🔍 Ask These Questions
- Was the threatened force unlawful and imminent? (Was a real attack coming right now, not later or long ago?)
- Did the defender hold a reasonable belief that force was necessary? (Would a sensible person in her shoes see the same danger?)
- Was the response proportional — deadly force only against a deadly threat? (Did she answer a shove with a push, not a bat?)
- Was the defender the initial aggressor, and if so, did she withdraw or face escalation? (If she started it, she must clearly quit before she can fight back.)
- Does the jurisdiction impose a duty to retreat? Majority: no. (Most states don't make you run away first, even from deadly danger.)
- Is the claim really defense of others or property, with their tighter limits? (Helping people follows the same rules; protecting stuff never allows deadly force.)
⚠️ Bar Trap
Exam language: Examiners plant an obvious safe avenue of escape and offer a distractor rejecting self-defense because the defendant failed to retreat. Under the majority rule there is no duty to retreat before using deadly force; retreat matters only if the facts specify a retreat jurisdiction, and even then never inside the defendant's own home.
ELI-10: An open exit does not ruin the defense. Most states let you stand your ground, so don't punish the defendant for staying.
🧪 Question
A nurse finishing a late shift walked to her car in a hospital parking garage. A man stepped from behind a pillar, raised a hunting knife, and said, "The purse, or I open you up," advancing toward her. A lit stairwell door stood ten feet behind the nurse, and she could have reached it safely before the man closed the distance. Instead, she drew a lawfully carried pistol and shot the man, seriously wounding him. She is charged with assault with a deadly weapon in a jurisdiction following the majority rules on self-defense.
Is the nurse's self-defense claim likely to succeed?
(A) No, because she failed to retreat through the stairwell door when she could have done so in complete safety. (B) No, because deadly force is unavailable when the attacker seeks only property. (C) Yes, because she reasonably believed deadly force was necessary to prevent imminent death or serious bodily injury. (D) Yes, but only if the garage qualifies as an extension of her workplace under the castle doctrine.
Answer: (C). The man threatened her with a knife at close range, creating a reasonable belief of imminent death or serious bodily injury. In a majority jurisdiction she had no duty to retreat, so the available stairwell is irrelevant and her proportional deadly response is justified.
💡 Why the Wrong Answers Are Wrong
- (A) applies the minority retreat rule; the majority imposes no duty to retreat before using deadly force.
- (B) mislabels the threat — the knife and the words threatened her body, not merely her purse.
- (D) invents a castle-doctrine requirement; under the majority no-retreat rule, no special location is needed.
- ELI-10: The misconception is believing you must always run first. In most states, standing your ground is allowed.
