(1) The House of Representatives shall be composed of not more than two hundred and fifty members, unless otherwise fixed by law, who shall be elected from legislative districts apportioned among the provinces, cities, and the Metropolitan Manila area in accordance with the number of their respective inhabitants, and on the basis of a uniform and progressive ratio, and those who, as provided by law, shall be elected through a party-list system of registered national, regional, and sectoral parties or organizations.
(2) The party-list representatives shall constitute twenty per centum of the total number of representatives including those under the party list. For three consecutive terms after the ratification of this Constitution, one-half of the seats allocated to party-list representatives shall be filled, as provided by law, by selection or election from the labor, peasant, urban poor, indigenous cultural communities, women, youth, and such other sectors as may be provided by law, except the religious sector.
... (Art. VI, Sec. 5)