Self-Defense Laws

Self-defense laws in the United States allow people to use force to protect themselves and others to avoid criminal liability for their actions. But the rules are narrower and more complicated than many expect, and each state has its own rules governing use of force in self defense. Any use of force that occurs outside the bounds of state law can result in a criminal conviction.

What Is Self-Defense?

In criminal law, self-defense is a legal justification for using force to protect yourself or someone else from an imminent threat of unlawful force. Defendants who claim self-defense admit that they used force or violence against the victim. Generally, claims of self-defense come into play when the defendant is accused of a violent crime, such as assault, battery, manslaughter, or murder.

To succeed, most states require that the person had a reasonable belief that force was necessary to defend against an immediate and unlawful threat, and the amount of force used was proportional to the threat.

Self-defense is not a free pass to use force against another. Prosecutors, judges, and juries look closely at what happened, what the person believed, and whether that belief and response were reasonable under the circumstances. Even when someone honestly feels afraid, using more force than the law allows can still result in criminal charges and having to go to trial.

What Are the Basic Rules for Self-Defense?

Defendants who raise a self-defense claim assert that they used force against the "victim," because the "victim" was the actual attacker. The core issues in any self-defense claim will typically be the following.

Who started it? Many states limit or deny self-defense to someone who started the fight, unless they clearly withdraw and the other person continues.

Was the fear of harm reasonable? The defender must have believed force was necessary, and a reasonable person in the same situation would have the same belief. (If the defender is wrong, an imperfect self-defense claim might apply. More on this issue below.)

Was the aggressor's force unlawful? The attacker must have been acting unlawfully. For example, a person can't defend against lawful police force and claim self-defense.

Was the threat imminent? The danger must have been immediate, not a vague or future possibility. Some states use the term imminent and others use immediate.

Was the force used proportional? The defender can only use as much force as is needed to protect themself or another from the unlawful attack. They cannot respond to minor threats with extreme, deadly force.

Understanding these elements helps explain why some high-profile self-defense claims succeed while others fail.

Examples of Self-Defense Rules

The most fundamental components required for a self-defense claim are proportionality, necessity, and reasonable belief.

Was the Defender's Use of Force Proportional to the Threatened Harm?

Proportionality means the response should roughly match the level of threat. For example, responding to a shove with a punch might be seen as nondeadly force against nondeadly force, but responding to a slap by brandishing a knife is likely excessive and disproportionate. However, imagine the defending person is a 5-foot tall woman with a broken leg and the slap comes from a 6-foot tall muscular man. Jurors might consider the woman's reaction in brandishing a knife to be a proportional response to the slap, considering the discrepancy in size and strength between the two persons.

Was the Defender's Use of Force Necessary and Reasonable?

Reasonable belief blends a person's actual fear with an objective standard. The law asks not just whether the defender was afraid, but whether an ordinary person in that situation could have reasonably believed that using that level of force was necessary to avoid imminent serious harm. These requirements often narrow self-defense claims that are driven by panic, bias, or misperception.

When Can a Person Use Deadly Force?

Deadly force is generally force that is likely to cause death or serious bodily injury, such as shooting a gun at someone, stabbing, or delivering severe blows with a heavy object. Even actions that are not meant to kill can count as deadly force if they carry a high risk of causing death or grave harm.

Defending Against Deadly Force

States usually allow deadly force only when a person reasonably believes it is necessary to prevent death, serious bodily harm, or certain violent felonies, such as kidnapping, sexual assault, or home invasion. Using deadly force to prevent minor injury or protect property is rarely justified. Courts also look at whether deadly force remained necessary throughout the incident. For instance, continuing to use deadly force after the threat has clearly passed can lead to criminal liability.

Imperfect Self-Defense

Some states recognize the doctrine of imperfect self-defense. Imperfect self-defense partially defends a killing when the defendant honestly, but unreasonably, believed deadly force was necessary to prevent imminent death or serious bodily harm. Unlike a "perfect" self-defense claim, which can lead to an acquittal, imperfect self-defense typically reduces a murder charge. Where recognized, a defendant may still be convicted and punished, but only for manslaughter, because the law treats an unreasonable, but genuine, fear differently from a malicious killing.

(Kan. Stat. § 21-5404 (2025); Faulkner v. State, 483 A.2d 759 (Md. 1984).)

Duty to Retreat vs. Stand Your Ground Laws

States generally split into two camps when it comes to whether an innocent person must retreat before using deadly force when attacked outside their home. They are either duty-to-retreat states or stand-your-ground states.

Duty to Retreat

A minority of states fall into the duty-to-retreat category. In duty-to-retreat states, a person must avoid using deadly force if they can safely escape the situation instead. The idea is that even someone who is threatened should not kill if they have a completely clear, safe way to avoid harm.

This duty usually applies only to deadly force, not lesser, nondeadly force such as pushing someone away. State laws generally state that retreat is not required unless the person can do so "with complete safety," meaning the law doesn't require someone to run away if doing so would increase their danger. Even in duty-to-retreat states, the rule often does not apply in the person's own home based on the castle doctrine (discussed below).

(N.J. Stat. § 2C:3-4 (2025).)

Stand Your Ground

Stand-your-ground (or no-retreat) laws remove the duty to retreat before using deadly force when a person:

• is in a location where they have a right to be, and
• reasonably believes deadly force is necessary to prevent death or serious bodily harm.

A majority of states have stand-your-ground laws. These laws don't eliminate other limits of self-defense—the defender still needs a reasonable belief in an imminent, serious threat and must not be the unlawful aggressor. Stand-your-ground laws have been politically controversial, with critics arguing such laws encourage escalation and supporters saying these laws protect the innocent and condemn the wrong.

(Mo. Rev. Stat. § 563.031 (2025).)

What Is the Castle Doctrine?

​The castle doctrine recognizes a person's right to stand their ground in their home. It applies in duty-to-retreat and stand-your-ground states. A person can use force, even deadly force, against someone who has unlawfully entered their home. While specifics of the law vary from state to state, people who are under attack in their own homes don't need to retreat or try to escape, even if they can do so safely.

Some states go further and create a legal presumption that a resident reasonably fears death or serious harm when an intruder unlawfully and forcibly enters their dwelling. Other jurisdictions extend castle-type protections to places like an occupied vehicle or a workplace.

(Cal. Penal Code § 198.5; Conn. Gen. Stat. § 53a-19; Fla. Stat. §§ 776.013; 776.031 (2025).)

Getting Legal Help

Because self-defense law varies significantly by state and fact pattern, anyone who carries a weapon or worries about personal safety should review their own state's statutes and talk to a legal expert if they have questions.

If you face criminal charges and feel you have a claim for self-defense, talk to a criminal defense attorney or ask for a public defender. An attorney can help defend your case and protect your constitutional rights.