Self Defense Laws: When and How Force Is Justified
Understand when self defense is legally justified, including rules for deadly force, defense of others, and how state laws like stand your ground apply. 7 min read updated on April 23, 2025
Key Takeaways
- Self defense is a legal justification for using force to prevent imminent harm.
- Force must be reasonable and proportionate to the threat faced.
- The right extends to defense of others and, in some jurisdictions, property.
- Deadly force is allowed only when necessary to prevent serious bodily harm or death.
- "Stand your ground" and "castle doctrine" laws affect duty to retreat and defense at home.
- Legal standards for self defense vary across states and often involve a reasonableness test.
Defense Versus Self-Defense
Self defense is a type of defense to certain criminal charges involving force, like murder. Use of force is justified when a person reasonably believes that it is necessary for the defense of oneself or another against the immediate use of unlawful force. However, a person must use no more force than appears reasonably necessary in the circumstances.
Force likely to cause death or great bodily harm is justified in self-defense only if a person reasonably believes that such force is necessary to prevent death or great bodily harm.
The Right to Protect One's Person and Property From Injury
It will be proper to consider the following:
- The extent of the right of self-defense.
- By whom it may be exercised.
- Against whom.
- For what causes.
Regarding the Extent of the Right of Self-Defense
First, when threatened violence exists, it is the duty of the person threatened to use all prudent and precautionary measures to prevent the attack. For example, if by closing a door which was usually left open, one could prevent an attack, it would be prudent, and perhaps the law might require, that it should be closed in order to preserve the peace, and the aggressor might in such case be held to bail for their good behavior.
Secondly, if after having taken such proper precautions, a party should be assailed, they may undoubtedly repel force by using force, but in most instances cannot, under the pretext that they have been attacked, use force enough to kill the assailant or hurt them after they have secured themself from danger. For example, if an unarmed person enters a house to commit a larceny, and while they are there they do not threaten any one, nor do any act which manifests an intention to hurt any one, and there are a number of persons present who may easily secure them, no one will be justifiable to do them any injury, much less to kill them.
The assailant ought to be secured and delivered to the public authorities. But when an attack is made by a thief under such circumstances, and it is impossible to ascertain to what extent they may push it, the law does not require the party assailed to weigh with great nicety the probable extent of the attack, and they may use the most violent means against their assailant, even to the taking of their life.
Homicide may be excused when a person has no other probable means of preserving their life from one who attacks them while in the commission of a felony, or even if in a sudden quarrel he beats them, so that they are reduced to this inevitable necessity. And the reason is that when a person is reduced to such vulnerability, they cannot call to their aid the power of society or of the commonwealth, and being unprotected by law, they reassume their natural rights which the law sanctions, of killing their adversary to protect themself.
Regarding Whom May Exercise Self-Defense
The party attacked may undoubtedly defend themself, and the law further sanctions the mutual and reciprocal defense of such as stand in the near relations of husband and wife, parent and child, and master and servant. In these cases, if the party themself or any of these their relations, is forcibly attacked in their person or property, it is lawful for them to repel force using force.
The law in these cases respects the passions of the human mind, and makes it lawful in them, when external violence is offered to themself, or to those to whom they bear so near a connection, to do that immediate justice to which they are prompted by nature and which no prudential motives are strong enough to restrain.
The party making the attack may be resisted, and if several persons join in such attack they may all be resisted, and one may be killed although they may not themself have given the immediate cause for such killing, if by their presence and their acts they have aided the assailant.
Regarding Against Whom a Person May Use Self-Defense
A person may repel force by force in defense of their person, property or habitation, against any one who manifests, intends, attempts, or endeavors, by violence or surprise, to commit a forcible felony, such as murder, rape, robbery, arson, burglary, and the like. In these cases he or she is not required to retreat, but may resist and even pursue the adversary, until they have secured themselves from all danger.
A person may defend their self against animals, and may during the attack kill them, but not afterwards.
Regarding the Cause for Self-Defense
The cases for which a person may defend themself are of two kinds; first, when a felony is attempted, and secondly, when no felony is attempted or apprehended.
- A person may defend themself and even commit a homicide for the prevention of any forcible and atrocious crime, which if completed would amount to a felony; and of course under the like circumstances mayhem, wounding, and battery would be excusable at common law.
- A person may defend themself when no felony has been threatened or attempted:
- When the assailant attempts to beat another and there is no mutual combat, such as where one meets another and attempts to commit or does commit an assault and battery on them, the person attacked may defend themself.
- When in an attempt to strike another, the assailant is sufficiently near so that that there is danger, the person assailed may strike first, and is not required to wait until they have been struck.
When There is No Cause for Self-Defense
When there is a mutual combat upon a sudden quarrel, both parties are the aggressors, and if in the fight one is killed it will be manslaughter at least, unless the survivor can prove two things:
- That before the mortal stroke was given they had refused any further combat, and had retreated as far as they could to safety.
- That they killed their adversary from necessity, to avoid their own destruction.
As a general rule no one is allowed to defend themself with force if they can apply to the law for redress, and the law gives them a complete remedy.
Legal Limits on the Use of Force
Even in cases of legitimate self defense, there are limits:
- Excessive Force: Using more force than necessary, especially deadly force when only minor harm is threatened, may lead to criminal liability.
- Provocation: A person who initiates a confrontation may not claim self defense unless they clearly disengage.
- Unlawful Possession of Weapons: Using a weapon unlawfully possessed can complicate or invalidate a self defense claim.
Defenders must carefully assess the threat and their own actions to ensure their response remains within the bounds of the law.
Factors That Influence Validity of Self Defense
Whether a claim of self defense is upheld in court depends on several factors:
- Immediacy of Threat: The threat must be immediate and not speculative or anticipated.
- Reasonableness of Perception: The belief that harm was imminent must be reasonable from the perspective of the person defending themselves.
- Proportionality of Response: The level of force used must be appropriate to the threat. Deadly force is typically justified only when facing a threat of death or serious bodily injury.
- Initiator of Force: If the defender provoked the attack, they may lose the right to claim self defense unless they attempted to withdraw and communicated that intent.
These factors are often weighed by judges or juries based on available evidence and witness credibility.
Burden of Proof in Self Defense Cases
The burden of proof in self defense cases can vary by jurisdiction:
- Prosecution's Burden: In many states, once a defendant presents some evidence of self defense, the prosecution must disprove the claim beyond a reasonable doubt.
- Defendant’s Burden: Other jurisdictions may require the defendant to prove their use of force was justified by a preponderance of the evidence.
This evidentiary standard plays a crucial role in trial outcomes and underscores the importance of presenting clear and credible facts supporting the perception of an imminent threat.
Self Defense Laws and Doctrines
Self defense laws differ by jurisdiction but generally rely on the principles of necessity and proportionality. Some key legal doctrines include:
- Stand Your Ground Laws: These laws eliminate the duty to retreat before using force in self defense, as long as the individual is lawfully present and reasonably perceives a threat. About half of U.S. states have enacted such laws.
- Castle Doctrine: Under this doctrine, individuals have no duty to retreat when defending themselves against an intruder in their home. Some jurisdictions extend this protection to vehicles or workplaces.
- Duty to Retreat: In states without Stand Your Ground laws, individuals may be required to retreat, if safely possible, before using deadly force.
Legal justification often hinges on whether the defendant reasonably believed that force was necessary to prevent imminent harm or death. Courts may assess the immediacy of the threat, availability of alternatives, and the level of force used in determining whether the defense is valid.
Frequently Asked Questions
-
What qualifies as self defense legally?
Self defense is a legal justification for using force to prevent imminent harm, provided the force used is proportionate and reasonable under the circumstances. -
Can I use deadly force to protect my property?
Generally, no. Deadly force is typically justified only to prevent serious bodily harm or death, not solely to protect property. -
What is the difference between stand your ground and castle doctrine?
Stand your ground laws allow individuals to use force without retreating in any place they are lawfully present. Castle doctrine applies this principle specifically to one’s home (and sometimes car or workplace). -
Do I have to wait to be attacked to claim self defense?
No. If there is an immediate threat of unlawful force, a person can act preemptively to protect themselves, provided the response is proportionate. -
Who decides if my use of force was reasonable?
A judge or jury typically evaluates the facts and determines if your perception of danger and use of force were legally reasonable based on the evidence presented.
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