VIGILANTE

[noun] [C] - a person who tries in an unofficial way to prevent crime, or to catch and punish someone who has committed a crime, esp. because they do not think that official organizations, such as the police, are controlling crime effectively. Vigilantes usually join together to form groups.Support for vigilantes is a reflection of the apparent breakdown of law and order.The Guardian Angels are a group of vigilantes who try to prevent crime on the New York subway.The area is patrolled by members of a vigilante group/force/patrol/squad.(figurative) Feminist groups proposed that vigilantes (= people who make certain that something is acceptable) should examine all the books on the students' reading list.