From New World Encyclopedia

Self defense refers to acts of violence committed for the purpose of protecting oneself. This justification may be extended to protection of another person, or to one's property. Although laws vary in different countries, generally the force used should be "reasonable" or comparable to the threat. Thus, deadly force can be included in self-defense, although only in cases of extreme peril. Generally, self-defense techniques, such as martial arts, stress avoiding or defusing physical confrontations before they escalate. However, when violence is imminent and unavoidable so that retreat is not an option, such as within one's own home, pre-emptive attacks may be sanctioned. While the use of violence, especially deadly force or pre-emptive attacks, is never the best solution to any situation and is ethically problematic, the concept of the right to defend oneself, one's family, and one's property from attack is a basic belief of human beings. The hope for a world where such defense against attack from other human beings is unnecessary is also a universal desire.


Self defense and defense of others (in the United States called alter ego defense or defense of a third person) convert what would otherwise have been tortious or criminal acts into excused (sometimes termed "justified") acts when committed for the purpose of protecting oneself or another person. This necessarily includes the use of violence and, sometimes, deadly force. In many jurisdictions, this defense may also be extended to acts in defense of property, although generally in such cases deadly force is not included.

Legal status of self defense

In most jurisdictions, when the defense succeeds, it operates as a complete justification provided the degree of violence used is comparable or proportionate to the threat faced, and so deadly force should only be used in situations of "extreme" danger. The defense would fail if a defendant deliberately killed a petty thief who did not appear to be a physical threat. Sometimes there is a "duty to retreat" which invalidates the defense. On the other hand, such "duty to retreat" may be negated in situations involving abusive relationships and in burglary situations, given the so-called castle exception argued by Edward Coke), namely that one cannot be expected to retreat from one's own home, namely, “a man’s house is his castle,” et domus sua cuique est tutissimum refugium and “each man’s home his safest refuge”) which brings self-defense back into play.

In some countries, the concept of "pre-emptive" self-defense is limited by a requirement that the threat be imminent. Thus, lawful "pre-emptive" self-defense is simply the act of landing the first blow in a situation that has reached a point of no hope for de-escalation or escape. This pre-emptive approach is recognized by many self-defense instructors and experts believe that if the situation is so clear-cut as to feel certain violence is unavoidable, the defender has a much better chance of surviving by landing the first blow and gaining the immediate upper hand and so quickly stop the risk to their person.


Early theories made no distinction between defense of the person and defense of property. Whether consciously or not, this built on the Roman Law principle of dominium, where any attack on the members of the family or the property it owned was a personal attack on the pater familias—the male head of the household, sole owner of all property belonging to the household, and endowed by law with dominion over all his descendants through the male line no matter their age (Frier & McGinn 2004).

In Leviathan (1651), Thomas Hobbes proposed the foundational political theory that distinguished between a "state of nature," where there is no authority, and a modern state. Hobbes argued that although some men may be stronger or more intelligent than others in their natural state, none are so strong as to be beyond a fear of violent death, which therefore justifies self-defense as man's highest necessity.

The inclusion of defense of one's family and home recognizes the universal benefit claimed to stem from the family's peaceable possession of private property. Further, it follows that laws must simultaneously criminalize aggression resulting in loss of this property or injury, but decriminalize qualitatively identical violence causing loss or injury because it is used in self-defense. As a resolution of this apparent paradox, libertarian Robert Nozick (1974) asserted that there are no positive "civil rights," only rights to property and the right of autonomy. In this theory, the "acquisition principle" states that people are entitled to defend and retain all holdings acquired in a just way and the "rectification principle" requires that any violation of the first principle be repaired by returning holdings to their rightful owners as "one time" redistribution. Hence, in default of self-defense in the first instance, any damage to property must be made good either in kind or by value.

Similarly, theorists such as George Fletcher and Robert Schopp have adopted European concepts of autonomy in their liberal theories to justify the right-holder using all necessary force to defend his or her autonomy and rights. This right inverts the felicitation principle of utilitarianism with the responsive violence being the greatest good to the individual, but accurately mirrors Jeremy Bentham, who saw property as the driving force to enable individuals to enhance their utilities through stable investment and trade. In liberal theory, therefore, to maximize the utility, there is no need to retreat nor use only proportionate force. The attacker is said to sacrifice legal protection when initiating the attack. In this respect, the criminal law is not the tool of a welfare state that offers a safety net for all when they are injured. Nevertheless, some limits must be recognized, such as where a minor initial attack simply becomes a pretext for an excessively violent response. The civil law systems have a theory of “abuse of right” to explain denial of justification in such extreme cases.

Defense of others

The rules of self-defense are the same when force is used to protect another from danger. Generally, the defendant must have a reasonable belief that the third party is in a position where he or she would have the right of self-defense. For example, a person who unknowingly chances upon two actors practicing a fight would be able to defend his restraint of the one that appeared to be the aggressor. Most courts have ruled that such a defense cannot be used to protect friends or family members who have engaged in an illegal fight. Likewise, one cannot use this to aid a criminal.

Defense of property

The defense of property is a possible justification used by defendants who argue that they should not be held liable for the loss and injury they caused because they were acting to protect their property. Courts have generally ruled that the use of force may be acceptable, but that "deadly force" is generally not acceptable in defending property, although it may be acceptable in self-defense or, in some countries, the defense of one's home. As deadly force is not allowed, the setting of booby-traps and the use of dangerous guard dogs is also either not allowed, or only allowed on strict terms such as the prominent display of warning notices.

National self-defense

In politics, the concept of national or mutual self-defense to counter a war of aggression refers to a defensive war organized by the state, and is one possible criterion in the Just War theory.

Self-defense in various countries

The laws relating to self-defense vary by country, as does their enforcement. Some significant examples, including discussion of some of the ethical issues involved and how the laws have been developed to address them, are described in the following sections.

United States

In the United States, the defense of self-defense allows a person attacked to use reasonable force in their own defense and the defense of others.

While the statutes defining the legitimate use of force in defense of a person vary from state to state, the general rule makes an important distinction between the use of physical force and deadly physical force. A person may use physical force to prevent imminent physical injury, however a person may not use deadly physical force unless that person is in reasonable fear of serious physical injury or death. Most statutes also include a "duty to retreat" (notable exceptions include Louisiana and Florida, which feature a "stand-your-ground" law), wherein deadly physical force may only be used if the person acting in self-defense is unable to safely retreat. A person is generally not obligated to retreat if in one's own home (for example, a person does not have to retreat from the living room to the kitchen, then to the bedroom, then to the bathroom) in what has come to be called the "castle exception."

United Kingdom

In English criminal law, the defense of self-defense provides for the right of people to act in a manner that would be otherwise unlawful in order to preserve the physical integrity of themselves or others or to prevent any crime.

Common law

Self-defense in English law is a complete defense to all levels of assault and cannot be used to mitigate liability, say, from a charge of murder to the lesser charge of manslaughter in a homicide where a soldier or police officer acting in the course of his duty uses a greater degree of force than necessary for self-defense (compare the situation in Australia). Hence, self-defense is distinguishable from "provocation," which only applies to mitigate what would otherwise have been murder to manslaughter, i.e. it is not a complete defense.

Self-defense is therefore interpreted in a relatively conservative way to avoid creating too generous a standard of justification. The more forgiving a defense, the greater the incentive for a cynical defendant to exploit it when planning the use of violence or in explaining matters after the event. Thus, although the jury in self-defense cases are entitled to take into account the physical characteristics of the defendant, that evidence has little probative value in deciding whether excessive force was actually used. The general common law principle is stated in Beckford v R (1988) 1 AC 130:

A defendant is entitled to use reasonable force to protect himself, others for whom he is responsible and his property.

Reasonable Force

Opinions can differ on what is a reasonable amount of force, but one thing is certain: the defendant does not have the right to decide how much force it is reasonable to use, because the defendant would always believe he or she was acting reasonably and would never be guilty of any offence. It is for the jury, as ordinary members of the community, to decide the amount of force which it would be reasonable to use in the circumstances of each case.

In R v Lindsay (2005) AER (D) 349, the defendant picked up a sword in self-defense when attacked in his home by three masked intruders armed with loaded handguns, and killed one of them by slashing him repeatedly with that sword. The prosecution case was that, although he had initially acted in self-defense, he had then lost his self-control and demonstrated a clear intent to kill the armed intruder. In fact, the defendant was himself a low-level cannabis dealer who kept the sword available to defend himself against other drug dealers. The Court of Appeal confirmed an eight-year term of imprisonment. In a non-criminal context, it would not be expected that ordinary householders who "go too far" when defending themselves against armed intruders would receive such a long sentence.


The modern law on belief is stated in R v Owino (1996) 2 Cr. App. R. 128 at 134:

A person may use such force as is [objectively] reasonable in the circumstances as he [subjectively] believes them to be.

To gain an acquittal, the defendant must fulfill a number of conditions. The defendant must "believe," rightly or wrongly, that the attack is imminent. Lord Griffith said in Beckford v R:

A man about to be attacked does not have to wait for his assailant to strike the first blow or fire the first shot; circumstances may justify a pre-emptive strike.

The issue of belief is more complicated when the defendant has consumed alcohol or drugs. In R v Letenock (1917) 12 Cr. App. R. 221, the defendant claimed mistakenly to believe that the victim was about to attack him. The judge directed the jury that his drunkenness was irrelevant unless he was so drunk as to be incapable of knowing what he was doing. The Court of Criminal Appeal quashed his conviction for murder and substituted a verdict of manslaughter. Lord Reading CJ said at 224:

The only element of doubt in the case is whether there was anything which might have caused the applicant, in his drunken condition, to believe that he was going to be struck.

This suggests that the question is whether there was any intelligible basis for the defendant’s belief. If so, the defendant is entitled to be judged on the facts as he believed them to be, regardless or whether his belief was reasonable.

Law enforcement by police officers

The use of force to prevent crime, including crimes against property, should be considered justifiable because of the utility to the community, i.e. where a police officer uses reasonable force to restrain or arrest a criminal or suspect, this bring the greatest good to the largest number of people. But, where the officers make mistakes, the law can be unpredictable.

A private citizen does have the power to arrest and, where it is lawfully exercised, may use reasonable force and other reasonable means to affect it.

The common law stands alongside s3(1) of the Criminal Law Act 1967, which provides that:

A person may use such force as is reasonable in the circumstances in the prevention of crime, or in effecting or assisting in the lawful arrest of offenders or suspected offenders or of persons unlawfully at large.

Law enforcement by soldiers

Since the "war on terror" began in 2001, the U.K. has seen a substantial increase in the use of armed police officers (and, sometimes, specialist counter-terrorism units including military personnel). The issue of the extent to which soldiers may be allowed to shoot a suspect in defense of themselves and others has therefore become more relevant to English law, although it has always been highly relevant given the role of the military in the policing of Northern Ireland. In AG for Northern Ireland's Reference (No 1 of 1975) (1977) AC 105, a soldier on patrol in Northern Ireland shot and killed an unarmed man, who ran away when challenged. The trial judge held that the prosecution had failed to prove that the soldier intended to kill or cause serious bodily harm, and that the homicide was justifiable under s3 Criminal Law Act (Northern Ireland) 1967 (identical wording to the English section). The House of Lords decided that the judge's ruling was purely one of fact, and, therefore, declined to answer the legal question of justification.


The Law Commission Report on Partial Defences to Murder (2004) Part 4 (pp. 78-86) rejected the notion of creating a mitigatory defense to cover the use of excessive force in self-defense, but accepted that the "all or nothing" effect can produce unsatisfactory results in the case of murder. For example, a battered woman or abused child using excessive force because he or she is physically at a disadvantage and not under imminent attack, would be denied a defense. Further, an occupier not being sure whether the proposed use of violence to defend his property against immediate invasion is reasonable, may feel forced to do nothing.

It was always possible that the same set of facts could be interpreted as either self-defense or provocation where there was a loss of control resulting in death. Thus, the commission recommended a redefinition of provocation to cover situations where a person acts lethally out of fear. This reflected the view of psychiatrsts that most people act in violent situations with a combination of fear and anger in their minds, and to separate the two emotions is not legally constructive.


In Sweden, the law of self-defense allows a person attacked to excuse or justify a proportionate use of violence in defense of the person or property.

Chapter 24 of the Swedish criminal code states various conditions for which a person will not be sentenced in court for committing an otherwise criminal act. Self-defense is considered grounds for non-conviction if the accused acted in a situation of peril and acted in a manner that is not "blatantly unjustifiable" in relation to that which is defended.

A situation of peril is stated to exist if:

  1. a person is subjected to, or is in imminent danger of being subjected to, a criminal attack against property or person, or
  2. a person through threats, force, or violence is prevented from taking back stolen property found on criminals "red handed," or
  3. an intruder attempts to enter a room, house, estate or ship, or
  4. another person refuses to leave a residence after being told to.

The interpretation of what is to be considered not "blatantly unjustifiable" is popularly expressed in Sweden as "that force which is required by the peril." In other words, the defending party may do whatever it takes so long as no alternative, less severe options are available. For example, if the defending party can flee a dangerous situation instead of engaging in a fight ("duty to retreat"). It should be noted that the expression "blatantly unjustifiable" allows fairly generous tolerance towards the defending party.

However, the defending party must also consider that which is defended and what injury is inflicted upon the attacker. If that which is defended is insignificant in comparison to the injuries to the attacker, the court may reject the claim that person acted in self-defense since the damage done to the attacker is "blatantly unjustifiable." Loss of life or permanent bodily injury rarely justifies self-defense unless the defending party was in danger of being subjected to the same.

For example, if the only way of stopping a criminal from escaping with stolen property would be by killing him, then it would not be justifiable to do so. This is because that which is defended (property) is not as valuable as a human life and therefore the action of killing the criminal is not justifiable.

Subjective peril

Swedish legal custom in regards to self-defense states that peril is subjective. This means that the peril is measured from what the defending party perceived as peril, and not the actual peril.

For example, if a person were to threaten someone with an unloaded gun (not a lethal threat), the defending party would not be convicted if defending themself as if the gun were loaded (a lethal threat). This is because the defending party may perceive the gun as loaded and thus lethal.


A person who commits acts which are "blatantly unjustifiable" while in peril may also escape conviction if the situation were such that the person "could not be expected to maintain control of himself." For instance, such a situation might be if the defending party was in a state of great fear or severe rage because of the peril.

Defense of others

The Swedish criminal code states that anyone who assists a defending party in peril shall have the same rights as the defending party.


In the criminal law of Australia, self-defense may be a complete defense to criminal liability for causing injury in defense of the person or, to a limited extent, property, or a partial defense to murder if the degree of force used was excessive.

In the South Australian Court of Criminal Appeal in R v Howe (1958) SASR 95, Mason J formulated six propositions on the law of self-defense which were accepted as a model direction on self-defense in murder trials. Thus, a full acquittal was achieved if the jury found that the accused had reasonably believed that he or she was being threatened with death or serious bodily harm and, if so, that the force used was reasonably proportionate to the perceived danger.

Excessive defense

The rationale of the defense recognizes that the degree of culpability normally associated with murder may be missing. In the High Court case of Viro v The Queen (1978) 141 CLR 88 Aickin J said at 180:

[There is] a real distinction in the degree of culpability of an accused who has killed having formed the requisite intention without any mitigating circumstance, and an accused who, in response to a real or a reasonably apprehended attack, strikes a blow in order to defend himself, but uses force beyond that required by the occasion and thereby kills the attacker.

Techniques of self-defense

Self-defense, as stated earlier, refers to actions taken by a person to defend oneself, one's property, or one's home. There is considerable debate as to what constitutes an acceptable level of physical force during self-defense. Some individuals prefer a limited pacifist response, while others advocate means up to and including deadly force, such as the use of firearms.

Forms of self-defense

Self-defense strategies form the basis of numerous martial arts, especially Asian martial arts, which usually provide self-defense classes as part of their curriculum.

Many schools of self-defense also teach strategies aimed at avoiding or defusing physical confrontations before they escalate. The curriculum for such courses commonly includes positioning strategies and strengthening the defender's self-confidence, which is assumed to discourage some physical attacks.


To defend our life, our property, and those closest to us is perhaps one of the oldest instincts we possess. This basic desire to protect ourselves and that which hold dear has grown from the individual to global proportions, influencing nations to make preemptive strikes in the interest of national security.

Self-defense in our modern age is used as a justification for actions that while unlawful, may not deserve punishment. There are, of course, restrictions on what can be considered self-defense, most importantly being the amount of force and the appropriateness to the situation in which it has been used (basically, not using a hammer as a fly-swatter). It can be agreed that in situations where life or great injury is at stake, defending one's self is more than acceptable by all moral standards. While the Christian teaching to "turn the other cheek" can be valued in small incidents without consequence, on a larger scale this attitude could have dire consequences.

Ethically there is some question about pre-emptive defense, or acting before another can attack you. The idea of acting on what one believes might take place in the future enters into fearsome territory where grave mistakes could be made. Ultimately, self-defense lays the burden of judgment on the attacked. One can only hope that we have learned how to respond appropriately to attack in such a way as to protect ourselves without inciting greater violence.

ISBN links support NWE through referral fees

  • Carpenter. 2003. “Of the Enemy Within, The Castle Doctrine, and Self-Defense.” Marquette Law Review 86 (4): 653.
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  • Dressler, Joshua. 1984. “New Thoughts About the Concept of Justification in the Criminal Law: A Critique of Fletcher's Thinking and Rethinking.” UCLA L. Rev. 32: 61.
  • Fletcher, George P. 1990. Crime of Self-Defense: Bernhard Goetz and the Law on Trial. Chicago: University of Chicago Press. ISBN 0226253341.
  • Fletcher, George P. 2000. Rethinking Criminal Law. Oxford: Oxford University Press. ISBN 0195136950.
  • Frier, Bruce W. and Thomas A.J. McGinn. 2004. A Casebook on Roman Family Law Oxford University Press.
  • Getman & Marshall. 2001. “The Continuing Assault on the Right to Strike.” Texas Law Review 79: 703.
  • Green. 1999. “Castles and Carjackers: Proportionality and the Use of Deadly Force in Defense of Dwellings and Property.” University of Illinois Law Review : 1.
  • McCoy. 2001. “The Homosexual-Advance Defense and Hate Crimes Statutes: Their Interaction and Conflict.” Cardozo Law Review 22: 629.
  • Maguigan. 1991. “Battered Women and Self-Defense: Myths and Misconceptions in Current Reform Proposals.” University of Pennsylvania Law Review 140: 79.
  • Metropolitan Police Service: Counter Terrorism Section
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  • Nozick, Robert. 1974. Anarchy, State, and Utopia. Basic Books. ISBN 0465002706
  • Schopp, Robert F. 1998. Justification Defenses and Just Convictions. Cambridge: Cambridge University Press. ISBN 0521622115.
  • Segev. 2005. "Fairness, Responsibility and Self-Defense." Santa Clara Law Review 45 (2): 383.
  • The Law Commission. Partial Defences to Murder
  • Texas Penal Code Chapter 9. Justification Excluding Criminal Responsibility. § 9.31/§ 9.44

External Links

All links retrieved January 25, 2023.


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