What is Board Of Civil Authority?

Legal Definition
A used in Vermont. This board is composed of the selectmen and justices of the peace of their respective towns. They are authorized to abate taxes, and the like.
-- Bouviers Law Dictionary
Legal Definition
In Vermont, in the case of a city this term includes the mayor and aldermen and justices residing therein; in the case of a town, the selectmen and town clerk and the justices residing therein ; in the case of a village, the trustees or bailiffs and the justices residing therein. Vt. St. 1894, 19, 59.
-- Black's Law Dictionary