Vigilantism (vɪdʒɪˈlæntɪzəm) is the act of preventing, investigating and punishing perceived offenses and crimes without legal authority.
A vigilante (borrowed from Spanish "vigilante", which means "sentinel" or "watcher", from Latin vigilāns) is a person who practices or partakes in vigilantism, or undertakes public safety and retributive justice without commission.
According to political scientist Regina Bateson, vigilantism is "the extralegal prevention, investigation, or punishment of offenses." The definition has three components:
Extralegal: Vigilantism is done outside of the law (not necessarily in violation of the law)
Prevention, investigation, or punishment: Vigilantism requires specific actions, not just attitudes or beliefs
Offense: Vigilantism is a response to a perceived crime or violation of an authoritative norm
Other scholars have defined "collective vigilantism" as "group violence to punish perceived offenses to a community."
Vigilantism and the vigilante ethos existed long before the word vigilante was introduced into the English language. There are conceptual parallels between the Dark Age and medieval aristocratic custom of private war or vendetta and the modern vigilante philosophy.
Elements of the concept of vigilantism can be found in the Biblical account in Genesis 34 of the abduction and rape (or, by some interpretations, seduction) of Dinah, the daughter of Jacob, in the Canaanite city of Shechem by the eponymous son of the ruler, and the violent reaction of her brothers Simeon and Levi, who slew all of the males of the city in revenge, rescued their sister and plundered Shechem. When Jacob protested that their actions might bring trouble upon him and his family, the brothers replied "Should he [i.e., Shechem] treat our sister as a harlot?"
Similarly, in , Absalom kills his brother Amnon after King David, their father, fails to punish Amnon for raping Tamar, their sister.
In the Western literary and cultural tradition, characteristics of vigilantism have often been vested in folkloric heroes and outlaws (e.