Necessary Defense: When Is It Self-Defense?

Quick Overview:
Necessary defense is an act by which a person repels an imminent or ongoing attack on an interest protected by criminal law. Such an act is not a crime unless the defense is clearly disproportionate to the nature of the attack. It is not necessary to wait for the first blow or to use a means of the same intensity as the attacker. However, the defense must be directed against an attack that is immediately imminent or ongoing; it cannot be justified as retaliation after the attack has ended. Necessary defense also exists under misdemeanor law.

Necessary defense as a circumstance precluding unlawfulness

Necessary defense is one of the circumstances precluding unlawfulness. This means that conduct which, under normal circumstances, might constitute a criminal offense or a misdemeanor, is not considered unlawful in a specific situation.

Typically, this involves a situation where the victim pushes the attacker away, uses pepper spray, defends themselves physically, or damages the attacker’s property to ward off the attack. If the legal conditions for necessary defense are met, it does not constitute a criminal offense.

Section 29 of the Criminal Code stipulates that an act that would otherwise be punishable, committed by a person to repel an imminent or ongoing attack on an interest protected by criminal law, is not a criminal offense. At the same time, however, it is not considered necessary defense if the defense was clearly disproportionate to the nature of the attack.

Necessary defense functions similarly in the context of misdemeanors. According to Section 25 of the Act on Liability for Misdemeanors and Proceedings Therein, an act by which a person repels an imminent or ongoing attack on an interest protected by law is not a misdemeanor, provided that the defense is not clearly disproportionate to the nature of the attack.

In everyday language, people often speak of “self-defense.” This term is understandable but legally narrower. Necessary defense does not apply only to the protection of oneself. You may also defend another person or protect property.

Necessary Defense and Extreme Necessity: How Do They Differ?

Self-defense and extreme necessity are often confused. Both can negate the unlawfulness of an act, but they function differently.

Self-defense responds to an attack. An attack is an unlawful act committed by a person, or by an animal used by a person as a weapon. Self-defense is directed against the attacker and is intended to repel the attack.

Extreme necessity responds to a danger. It does not have to involve an attack by a person. The danger may arise, for example, from a natural event, a technical malfunction, a medical condition, a traffic situation, or an act by a person that is not an attack. Section 28 of the Criminal Code stipulates that an otherwise criminal act by which a person averts an imminent danger to an interest protected by criminal law is not a criminal offense; however, extreme necessity does not apply if it was possible to avert the danger by other means or if the resulting consequence is clearly as serious or more serious than the one that was imminent.

Example of necessary defense: An attacker swings a metal bar at you, and you push him away so that he cannot complete the attack.

Example of extreme necessity: A driver swerves and damages a parked car to avoid a child who ran into the street.

The distinction is also important because, in cases of extreme necessity, the possibility of averting the danger by other means and the proportionality of the consequences are assessed more strictly. In cases of necessary defense, the law does not require the defender to choose the least harmful option. The limit is only when the defense is clearly disproportionate.

Conditions for Necessary Defense

For an act to constitute necessary defense, several conditions must be met. There must be an attack; the attack must be imminent or ongoing; it must be directed against a legally protected interest; and the defense must not be manifestly disproportionate to the nature of the attack.

Necessary defense is assessed based on the specific circumstances. The defense against a drunk person shoving patrons in a bar will differ from that against an attacker with a knife in an underpass. Important factors include the strength and number of attackers, the weapon used, the location, the time, the physical characteristics of the individuals involved, the intensity of the attack, the possibility of calling for help, and how quickly the situation unfolded.

Courts and administrative authorities should not evaluate self-defense merely in the convenient hindsight of a “desk review.” What matters is how the attack appeared to the defender at the moment the decision was made. In a civil case concerning Section 2905 of the Civil Code, the Supreme Court noted that the proportion between the threatened harm and the harm caused to the attacker is assessed based on how the attacker’s actions appeared to the person warding them off.

However, this does not mean that subjective fear alone is sufficient. There must be specific circumstances that justify the attack or its imminent threat.

An Imminent or Ongoing Attack

Necessary defense is permissible against an attack that is imminent or ongoing. You do not have to wait until the attacker actually strikes you. If it is already clear from the circumstances that an attack is about to occur, you may defend yourself.

An imminent attack could be, for example, a situation where an attacker draws a knife, winds up to strike, breaks into an apartment, approaches you with a club and threatens to use violence, or attempts to snatch a bag from your hand.

An ongoing attack is one that is currently taking place. For example, the attacker is hitting you, holding you, choking you, trying to drag you away, taking something from you, or continuing to act violently.

Necessary self-defense, on the other hand, does not cover retaliation. If the attacker has already fled, is lying motionless on the ground, has been subdued, or it is clear that the danger has ended, a further attack on them may no longer constitute self-defense. In such a situation, what was self-defense may become a criminal offense or a misdemeanor.

Example: If someone strikes you and is immediately about to strike again, you may defend yourself. However, if the attacker leaves the scene and you catch up to and attack them a few minutes later, it will be difficult to argue that you are still fending off an ongoing attack.

Attacks on Health, Liberty, Dignity, or Property

Necessary defense protects interests safeguarded by law. Most often, these include life, health, personal liberty, human dignity, the right to privacy, or property. Therefore, it need not involve only a physical assault.

Necessary defense may apply, for example, in the case of an attack on a person, an attempted robbery, a violent break-in, an attempt to steal property, or an attack on another person. However, the defense must always be aimed at repelling the attack.

If a police officer is lawfully carrying out an intervention—such as detaining a person in accordance with legal requirements—this does not constitute an unlawful attack. As a general rule, it is not possible to defend oneself against a lawful intervention by invoking self-defense. It would be a different matter if a public official were clearly acting outside the bounds of the law; however, such situations must be assessed very carefully and based on the specific circumstances.

Necessary defense may also be directed against an attack by a child or a person suffering from a mental disorder. An attack may also consist of the actions of a person who is not criminally responsible. However, this does not mean that it is appropriate to use the same level of force as against an armed adult attacker. It is precisely the circumstances of the attack and the identity of the attacker that will be crucial in determining whether the defense was not clearly disproportionate.

Does the defense have to be proportionate?

The law does not state that the defense must be exactly the same as the attack. Therefore, it is not the case that you may respond to a slap only with a slap, or to a knife only with a knife. Necessary defense is intended to repel the attack and may therefore be more intense than the attack itself.

The threshold is when the method of defense is clearly disproportionate to the attack. This is an important distinction. It is not enough that the defense was “slightly stronger.” It must be a clear excess, where the disproportion between the attack and the defense is evident at first glance.

Example of reasonable self-defense: A woman is confronted at night by a man who corners her with a knife and threatens her. She uses pepper spray so she can escape. Such conduct typically falls under the category of necessary self-defense.

Example of a clearly disproportionate defense: A store owner shoots at a child running away with a chocolate bar, even though there is no danger to life or health. Such conduct would very likely fall outside the bounds of necessary defense.

When assessing proportionality, the nature of the attack is the primary consideration. Important factors include the weapon used, the number of attackers, physical superiority, the location, the time of day, the possibility of escape, prior threats, the intensity of the attack, and whether the defender was acting under stress and time pressure.

Do I have to run away before the attack?

Necessary defense is not an extreme emergency. In cases of necessary defense, the law does not require the defender to first retreat, flee, or seek another option if facing an imminent or ongoing attack. The legal test does not hinge on whether it was possible to avert the attack in another way, but on whether the defense was not clearly disproportionate to the nature of the attack.

However, this does not mean that it is always reasonable to escalate a conflict. From a safety perspective, retreat is often the best solution. Legally, though, one cannot simply say that someone who did not flee cannot invoke self-defense.

The situation where a person in an underpass has no realistic possibility of leaving will be assessed differently from a situation where someone voluntarily continues a mutual scuffle, even though they could have safely left and the attack had effectively ended.

Defense of Another Person and Property

Necessary defense is not limited to self-defense. You can also defend another person. If you see someone attacking a store clerk, a child, a neighbor, or a random passerby, the law does not prohibit you from intervening.

Practical example: You arrive at a gas station and see an assailant pointing a knife at the attendant and demanding money. If you try to fend off the attack in a manner reasonable under the circumstances, this may constitute assistance in self-defense.

Necessary defense can also protect property. However, it is important to distinguish the intensity of the attack. Defense against a violent home invasion will look different than defense against someone stealing fruit from a garden. The smaller the potential harm, the more carefully you must choose your means of defense.

When it comes to property, the question often arises as to whether the defense was still actually warding off the attack. For example, if a thief is fleeing with an item and it is still possible to prevent the theft from being completed or to recover the item, defense may be considered. If the attack is already over and it is not a case of immediate self-defense, other measures come into play: calling the police, witnesses, surveillance footage, filing a criminal complaint, or seeking compensation for damages.

Attack by an Animal

In the case of an animal, it depends on what provoked the attack. If you are attacked by a dog that the owner intentionally set upon you, the dog may effectively be an instrument of human attack. In that case, the situation may be assessed as necessary defense against an attack carried out through an animal.

However, if the animal acts on its own—for example, if it escapes from a property and attacks without anyone using it as a tool—the situation will more often be considered a case of extreme necessity under the law. The goal is to avert the danger, not to repel an attack by a person.

In both cases, the response must be proportionate to the situation. Different measures will be appropriate for an attack by a large dog on a child than for a minor incident involving an animal that can be safely shooed away.

Firearms, Pepper Spray, and Self-Defense at Home

The use of a defensive tool does not automatically constitute excessive force. This may include pepper spray, a telescopic baton, a legally owned firearm, a common household item at hand, or physical force. Legally , it is not just the tool itself that is assessed, but the entire context of the attack.

What matters is what the defense was directed against. The use of pepper spray against an attacker with a knife will be evaluated differently than its use against a person who is merely shouting insults from a greater distance. Defense at night in one’s own apartment against a person breaking in will be assessed differently than a conflict on the street following a mutual argument.

The use of a firearm is an extremely serious matter and will always be examined very carefully. In and of itself, it is not ruled out that the use of a firearm could constitute necessary self-defense, but it must correspond to the nature of the attack. Defense against a threat to life or serious violence may be assessed differently than defense against minor property damage.

When it comes to self-defense at home, there is no simple rule such as “I can do anything in my own apartment.” Freedom of the home and the security of one’s dwelling are strongly protected values, but even here, the limit of obvious disproportion applies.

A Provoked Conflict and Excessive Use of Necessary Defense

An argument or prior conflict alone does not automatically preclude necessary self-defense. If a verbal dispute escalates into an unlawful physical attack, the victim may defend themselves.

The problem arises when someone deliberately provokes a conflict precisely to gain a pretext for an attack. Typically, a person provokes another over a long period, escalates the situation, waits for the first reaction, and then uses disproportionate violence. In such a situation, the claim of self-defense will be weak.

Excess in self-defense can take two forms. The first occurs when the defense comes too early or too late—for example, a preemptive strike against someone who might attack in a week, or retaliation after the attack has ended. The second occurs when the defense is clearly disproportionate to the nature of the attack.

Example: If an attacker is holding you by the throat and you kick him to free yourself, this may constitute self-defense. However, if you continue kicking after he has fallen and is clearly unable to continue the attack, your further actions may be deemed an attack on your part.

Damages and Civil Law

Necessary defense is relevant not only in criminal and misdemeanor law but also in civil liability for damages. Section 2905 of the Civil Code stipulates that a person who repels an imminent or ongoing unlawful attack against themselves or another person and thereby causes harm to the attacker is not liable for compensation. However, this does not apply if it is evident that, given the circumstances, the victim faced only minor harm or if the defense was clearly disproportionate, particularly in light of the severity of the harm caused to the attacker.

In practice, this means that an attacker is not automatically entitled to compensation for harm simply because he or she sustained injuries during the attack. However, if the defender clearly exceeded the limits of necessary defense, not only criminal or misdemeanor liability may be addressed, but also compensation for property damage or non-property harm.

Under civil law, the nature of the attack as perceived by the defender at that moment is also taken into account. The Supreme Court has explicitly emphasized that the proportion between the threatened and actual harm is assessed based on how the attack appeared to the person who was fending it off.

What to Do After the Incident

If you defended yourself against an attack, it is important to think not only about your immediate safety but also about evidence. It is often the evidence that determines whether the situation will be assessed as necessary defense or as unlawful conduct.

In practice, we recommend:

• call the police if the attack was serious, if there were injuries, if a weapon was involved, or if there is a risk of the conflict continuing,
• call for medical assistance if anyone is injured,
• obtain contact information for witnesses,
• take photos of the scene, damaged property, and any injuries,
• request a medical report,
• Find out if there is any surveillance footage,
• do not embellish your description of the incident or present assumptions as facts,
• create your own timeline of the incident as soon as possible.

In practice, it’s important to know who called the police first, how they described the situation immediately after the incident, whether their account matches the injuries, surveillance footage, and witness statements, and whether the timeline is logical.

The most common mistake is to downplay the situation or, conversely, to dramatize it. In cases of self-defense, the most important thing is to describe precisely why you perceived the attack as imminent or ongoing, what the attacker was doing, how close they were, whether they had a weapon, how you tried to fend off the attack, and when you stopped defending yourself.

Practical Examples of Necessary Defense

Pepper spray against an attacker with a knife: Ms. Dvořáková is walking home in the evening. A man stops her, pulls out a knife, threatens her, and approaches her. Ms. Dvořáková uses pepper spray and runs away. This is a typical situation that could constitute necessary defense, because an attack was imminent and the defense was aimed at warding it off.

Suspicion without an attack is not enough: Ms. Dvořáková feels that an unknown man is following her on the street. However, the man does not threaten her in any way, does not approach her aggressively, and is simply looking for the way to the bus stop. If Ms. Dvořáková were to preemptively attack him with a knife, it would very likely not constitute necessary self-defense. There would be no imminent or ongoing attack.

The saleswoman’s defense: A customer in a store physically attacks a saleswoman and tries to strike her. Another customer pushes the attacker away and restrains him until the police arrive, without continuing the violence after the attack has ended. This may constitute assistance in necessary self-defense.

Retaliation after the attack has ended: A man strikes another man and then leaves the restaurant. The victim runs after him into the street and, a few minutes later, attacks him from behind. This is no longer a matter of repelling an ongoing attack, but rather retaliation.

Defense of property: A homeowner catches someone breaking into his garage at night. He calls the police and pushes the intruder away from the door when the intruder tries to continue the forced entry. Depending on the circumstances, this may constitute necessary defense of property and the right to be free from intrusion in one’s home. However, the situation would be assessed differently if the intruder had already fled and the homeowner subsequently attacked him.

Summary

Necessary defense is a legal concept that allows one to repel an imminent or ongoing attack on an interest protected by law. If its conditions are met, an act that would otherwise be a criminal offense is not a criminal offense, and similarly, an act that would otherwise be a misdemeanor is not a misdemeanor.

The defense need not be as strong as the attack, and the defender need not wait for the first blow. However, it must not be manifestly disproportionate to the nature of the attack. Necessary defense differs from extreme necessity in that it responds to an attack, whereas extreme necessity responds to danger in general.

After the incident, it is essential to secure evidence: witnesses, medical reports, photographs, surveillance footage, and a precise timeline. In practice, it is often not just the mere assertion of “I was defending myself” that is decisive, but whether the circumstances actually corresponded to an imminent or ongoing attack.