(Originally) a committee having responsibility for public amenities, the maintenance of law and order, etc.; (later) a local government board or committee set up to oversee the activities of a local police force.
Origin
Late 18th century.
Definition of police board in US English:
police board
noun
(Originally) a committee having responsibility for public amenities, the maintenance of law and order, etc.; (later) a local government board or committee set up to oversee the activities of a local police force.