a committee of citizens set up to watch over and protect the interests of a community, faction, etc., often according to their own definition of "interests."
1836  (1848-1866)  In most of the places of these meetings Vigilance Committees have been formed and the registration commenced, and in some of them, delegates have been named to the proposed general meeting.
1897  Knots of people can be seen at every street corner considering the advisability of holding a mass meeting and forming a vigilance committee for the purpose of dealing in a summary manner with the jumpers.
1921  When word came of this murder the vigilance committee of Yale formed a rifle company of forty... .