Enforcing social morals by banding a group of citizens together to capture, examine and judge in summary fashion, and punish transgressors of law or morality.
Due to an upsurge in crime, the owners of 20 bars in central Vienna, Austria, legally hired, in 1994, a firm of gun-carrying private detectives in military-style uniforms accompanied by rotweiler dogs, to patrol the streets at night to maintain law and order. The New York-based "Guardian Angels" organization has established groups in Britain, Germany, and Sweden. They carry out safety patrols on public transport.
Vigilantism leads to the breakdown of law and civil order.
The natural outcome of vigilantism is that the strongest person or persons define social morals, resulting in a dictatorship.