Self-defense or private defense (see spelling differences) is a countermeasure that involves defending oneself, one's property, or the well-being of another from harm. The use of the right of self-defense as a legal justification for the use of force in times of danger is available in many jurisdictions, but the interpretation varies widely.
Physical self-defense is the use of physical force to counter an immediate threat of violence. Such force can be either armed or unarmed. In either case, the chances of success depend on a large number of parameters, related to the severity of the threat on one hand, but also on the mental and physical preparedness of the defender.
Many styles of martial arts are practiced for self-defense or include self-defense techniques. Some styles train primarily for self-defense, while other martial or combat sports can be effectively applied for self-defense. Some martial arts train how to escape from a gun situation, or how to break away from a punch, while others train how to attack. To provide more practical self-defense, many modern day martial arts schools now use a combination of martial arts styles and techniques, and will often customize self-defense training to suit the participants' lifestyles, occupations, age groups and gender, and physical and mental capabilities.
A wide variety of weapons could potentially be used for self-defence. Which is most suitable depends on those to be protected, the training of weapon user - and the situation and level of threat.
In many cases there are also legal restrictions. While in some jurisdictions firearms may be carried openly or concealed expressly for this purpose, there are more commonly strict restrictions on who can own firearms, and what types they can own. Knives, especially those categorized as switchblades may also be controlled, as may batons, pepper spray and personal stun guns and Tasers - although some may be legal to carry with a licence or for certain professions.
Everyday objects, such as flashlights, baseball bats, newspapers, keyrings with keys, kitchen utensils and other tools, and hair spray aerosol cans in combination with a lighter, can also be used as improvised weapons for self-defense. Tie-wraps double as an effective restraint. Weapons such as the Kubotan (pocket stick) have been built for ease of carry and to resemble everyday objects. Tactical flashlights and tactical pens are especially built as impact weapons that resemble everyday objects. Ballpoint pen knives, swordsticks, cane guns and modified umbrellas are similar categories of concealed self-defense weapons that serve a dual purpose.
Other forms 
Being aware of and avoiding potentially dangerous situations is an emphasis of self-defense. Attackers are typically larger, stronger, and are often armed or have an accomplice. These factors make fighting to defeat the attacker unlikely to succeed. When avoidance is impossible, one often has a better chance at fighting to escape, such methods maybe referred to as 'break away' techniques.
Verbal Self Defense aka 'Verbal Judo' is defined as using one's words to prevent, de-escalate, or end an attempted assault. It is a way of using words as weapons. This kind of 'conflict management' is the use of voice, tone, and body language to calm a potentially violent situation before violence actually ensues. This often involves techniques such as taking a time-out, and deflecting the conversation to individuals in the group who are less passionately involved.
- Author Katy Mattingly defines verbal self-defense as simply saying no to someone or repeatedly refusing a request or telling someone who has violated a boundary what you want, or it could entail a more complicated scenario in which you are called on to refuse to engage verbally with someone manipulative, to set limits, and end the conversation.
- Suzette Haden Elgin the author of The Gentle Art of Verbal Self-Defense states that verbal self-defense defends against the eight most common types of verbal violence, and redirects and defuses potential verbal confrontations.
Personal alarms 
Personal alarms are a way to practice passive self-defense. A personal alarm is a small, hand-held device that emits strong, loud, high pitched sounds to deter attackers because the noise will draw the attention of passersby. Child alarms often function as locators or device alarms such as triggering an alert when a swimming pool is in use to help prevent dangerous situations in addition to being a deterrent against would-be aggressors.[unreliable source?]
Self-defense education 
Self-defense techniques and recommended behavior under the threat of violence is systematically taught in self-defense classes. Commercial self-defense education is part of the martial arts industry in the wider sense, and many martial arts instructors also give self-defense classes. While all martial arts training can be argued to have some self-defense applications, self-defense courses are marketed explicitly as being oriented towards effectiveness and optimized towards situations as they occur in the real world. It should not be presumed however that sport based systems are inadequate, as the training methods employed regularly produce well conditioned fighters experienced in full contact fighting. There are a large number of systems taught commercially, many tailored to the needs of specific target audiences (e.g. defense against attempted rape for women). Notable systems taught commercially include:
- civilian versions of modern military combatives, such as kapap, Krav Maga, Systema.
- self-defense oriented forms of jujitsu, such as Bartitsu, Kodokan Goshin Jutsu, and Jigo Tensin-Ryu Jujutsu.
- rape prevention, including Rape Aggression Defense System (RAD), AWARE, IMPACT/Model Mugging, etc.
- Reality-Based Self-Defense (RBSD), Defensive Tactics.
- Sport based systems, such as Karate, Muay Thai, Boxing, Judo, BJJ, and Wrestling.
Legal aspects 
The self-defense laws of modern legislation build 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. In Leviathan (1651), Hobbes argues that although some 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 justifies self-defense as the highest necessity. In his 1918 speech Politik als Beruf (Politics as a Vocation), Max Weber defined a state as an authority claiming the monopoly on the legitimate use of force within defined territorial boundaries. Modern libertarianism characterizes the majority of laws as intrusive to personal autonomy and, in particular, argues that the right of self-defense from coercion (including violence) is a fundamental human right. In this context, note that Article 12 Universal Declaration of Human Rights states:
- No one shall be subjected to arbitrary interference with his privacy, family, home or correspondence, nor to attacks upon his honour and reputation. Everyone has the right to the protection of the law against such interference or attacks.
Combined with the principle of the state's monopoly of legitimate force, this means that those authorized by the state to defend the law (in practice, the police) are charged with the use of necessary force to protect such rights. The right to self-defense is limited to situations where the immediate threat of violence cannot be prevented by those authorized to do so (in practice, because no police force is present at the moment of the threat). The right to self-defense granted by law to the private citizen is strictly limited. Use of force that goes beyond what is necessary to dispel the immediate threat of violence is known as excessive self-defense (also self-defense with excessive force, excessive self-defense). The civil law systems have a theory of "abuse of right" to explain denial of justification in such cases. Thus, in English law, 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. It must be reasonable."
Similar clauses are found in the legislation throughout the western world. They derive historically from article 6 of the French Penal Code of 1791, which ruled that "manslaughter is legitimate if it is indispensably dictated by the present necessity of legitimate defense of oneself or others". The modern French penal code further specifies that excessive self-defense is punishable due to "disproportion between the means of defense used and the gravity of the attack" defended against.
The evaluation of whether use of force was excessive in a given case can be a difficult task. The British Law Commission Report on Partial Defenses to Murder (2004) Part 4 (pp78/86) recommends a redefinition of provocation to cover situations where a person acts lethally out of fear. This reflects the present view of psychiatrists that most people act in violent situations with a combination of fear and anger in their minds, and to separate these two types of affect is not legally constructive. In practice, self-defense laws still do make this distinction. German criminal law (§ 33) distinguishes "asthenic affect" (fear) from "sthenic affect" (anger). Excessive self-defense out of asthenic affect is not punishable.
Outside of the western world, justifiable self-defense tends to be interpreted more loosely, including the right to defend against any criminal act, without limitations to reasonable or proportionate use of force based on the magnitude of the crime. Instead, it may simply be the minimum amount of force required to stop the criminal, which may be lethal even for relatively small crimes. Thus, the Intermediate People's Court of Foshan, People's Republic of China in a 2009 case ruled as justifiable self-defense the killing of a robber who was trying to escape, because "the robbery was still in progress" at this time.
See also 
|Look up self-defense in Wiktionary, the free dictionary.|
- Anti-theft system
- Armored car
- Body armor
- Digital self-defense
- Door security
- Filipino martial arts
- Gated community
- GPS tracking unit
- Guard dog
- Hand to hand combat
- Intrusion alarm
- List of Taekwondo techniques
- Peroneal strike
- Physical security
- Safe room
- Secure telephone
- Video surveillance systems
- Ballistic knife
- Boot knife
- Brass knuckles
- Club (weapon)
- Defense wound
- Gun safety
- Hiatt speedcuffs
- Hollow-point bullet
- Laser pointer
- Laser sight
- Mace (spray)
- Millwall brick
- Paintball gun
- PAVA spray
- Personal defense weapon
- Slapjack (weapon)
- Stun grenade
- Throwing knife
- Tranquilizer gun
- Weighted-knuckle glove
Legal and moral aspects
- Dictionary.com's Definition of "Self-Defense". Dictionary.reference.com. Retrieved on 2012-06-02.
- Kopel, David B.; Gallant, Paul and Eisen, Joanne D. (2008). "The Human Right of Self-Defense". BYU Journal of Public Law (BYU Law School) 22: 43–178.
- Branded a criminal - Red Offender spray is rolled out at Canterbury's nightspots (KentOnLine.co.uk, 13 May 2010). Retrieved on 2012-08-05.
- Kubotans offering multiple uses. Themartialist.com (2001-09-11). Retrieved on 2012-06-02.
- Campco Uzi Tactical Pen (Tactical-Life.com). Retrieved on 2012-08-05.
- Self Defense Beginners' Handbook from Via Potentia Self Defense Center, ~300 pages. (PDF) . Retrieved on 2012-06-02.
- "Urban Dictionary". Retrieved 2010-07-28.
- Mattingly, Katy (2007-07). Self-defense: steps to survival By Katy Mattingly. ISBN 978-0-7360-6689-1. Retrieved 2010-07-28.
- Elgin, Suzette Haden (1980). The Gentle Art of Verbal Self-Defense. ISBN 978-0-88029-257-3. Retrieved 2010-07-28.
- Child Safety Alarms at LoveToKnow Safety. Safety.lovetoknow.com. Retrieved on 2012-06-02.
- The R.A.D. Systems of Self Defense. Rad-systems.com. Retrieved on 2012-06-02.
- We are AWARE. Aware.org (2011-12-09). Retrieved on 2012-06-02.
- a term coined in 1999 by Jim Wagner, taught as "Reality-Based Personal Protection" from 2003.
- See generally, Frier & McGinn, A Casebook on Roman Family Law, Oxford University Press (2004).
- L'homicide est commis légitimement, lorsqu'il est indispensablement commandé par la nécessité actuelle de la légitime défense de soi-même et d'autrui.
- disproportion entre les moyens de défense employés et la gravité de l'atteinte, Article 122-5.
- Are There Limits to Self-Defense? Beijing Review, 28 April 2009.