The law on self-defence in the USA can be used as a guideline. A person is privileged to use such force as reasonably appears necessary to defend herself against an apparent threat of unlawful and immediate violence from another. However, for the defendant to have acted in lawful self- defence the following elements must be established: (a) that the defendant believed that both the force used was necessary for her own protection and that this belief was reasonable; (b) that the threatened harm was imminent, i.e. that it would be inflicted immediately if she did not act in self-defence; (c) that the threatened harm was unlawful; (d) that the force used was reasonable, and was no more than appeared necessary under the circumstance. This means that deadly force can be used in self-defence only if it was believed that the other person was about to inflict death or great bodily injury. Only a minority of states still adhere to the common law rule that the defendant has a duty to retreat before using deadly force in self defence, except when it cannot be done in complete safety or where the defendant is attacked in her own home or place of work. "Imperfect" self-defence does not satisfy all of the above conditions, and may result in criminal charges being laid against the defendant.
In many countries legislation prohibits citizens from carrying arms or using them in self-defence. Physical self-defence resulting in harm to the attacker may lead to prosecution of the victim. The most famous recent case of private vigilantism involved Bernard Goetz who shot and wounded 5 youths he accused of attempting to rob him in a New York subway. He was brought to trial for attempted homicide and both he and his case became the basis for worldwide heated debate both condemning and condoning his action.
Minorities subject to physical harassment and attack on their homes may be deprived of any right to defend themselves. During the course of 1992-3, Bosnian Muslims were repeatedly refused the right by the international community to obtain arms in order to defend themselves against Serbian aggression. Bengali youths who defended themselves against a violent racial attack in London, UK, were arrested and charged with grievous bodily harm and violent disorder. They had to wait over one year to be tried and acquitted of the charge. Of special concern is the case of women subjected to repeated physical violence by their husbands and who are ultimately driven to kill their assailants in self-defence. Legal systems currently fail to recognize any extenuating circumstances or to recognize the right of such women to self-defence.