[citation needed] The key to this legal defense is that it was reasonable for the subject to believe that there was an imminent and otherwise unavoidable danger of death or grave bodily harm to the innocent by the deceased, when they committed the homicide.
Article 2 Paragraph 2 of the European Convention On Human Rights provides that death resulted from defending oneself or others, arresting a suspect or fugitive, or suppressing riots or insurrections, will not contravene the Article when the use of force involved is "no more than absolutely necessary": In South Africa, §49 Criminal Procedure Act of 1977[5] provided the following before its amendment in 1998: A non-criminal homicide ruling, usually committed in self-defense or in defense of another, exists under United States law.
The victim must reasonably believe, under the totality of the circumstances, that the assailant intended to commit a criminal act that would likely result in the death or life-threatening injury of an innocent person.
A homicide performed out of vengeance, or retribution for action in the past, or in pursuit of a "fleeing felon" (except under specific circumstances) would not be considered justifiable.
In the states of Alabama, Alaska, Arizona, California, Colorado, Connecticut, Florida, Georgia, Hawaii, Indiana, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Mississippi, Missouri, Montana,[6] New Jersey, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, West Virginia, Washington, Wyoming and other Castle Doctrine states, there is no duty to retreat in certain situations (depending on the state, this may apply to one's home, business, or vehicle, or to any public place where a person is lawfully present).