Local Government Code of 1991
Section 508. Organization.
(a) Vice-governors, vice-mayors, sanggunian members of barangays, municipalities, component cities, highly-urbanized cities and provinces, and other elective local officials of local government units, including those of the Metropolitan Manila Area and any metropolitan political subdivisions, may form their respective leagues or federation, subject to applicable provisions of this Title and pertinent provisions of this Code;
(b) Sanggunian members of component cities and municipalities shall form a provincial federation and elect a board of directors and a set of officers headed by the president. The duly elected president of the provincial federation of sanggunian members of component cities and municipalities shall be an ex-officio member of the sangguniang panlalawigan concerned and shall serve as such only during his term of office as president of the provincial federation of sanggunian members of component cities and municipalities, which in no case shall be beyond the term of office of the sanggunian panlalawigan concerned.