The Philippines has been governed under three constitutions, the first of which was promulgated in 1935, during the period of U.S. administration. It was closely modeled on the U.S. Constitution and included provisions for a bicameral legislative branch, an executive branch headed by a president, and an independent judiciary.

During the period of martial law (1972-81) under President Ferdinand E. Marcos, the old constitution was abolished and replaced by a new constitution (adopted in January 1973) that changed the Philippine government from a U.S.-style presidential system to a parliamentary form; the president became head of state, and executive power was vested in a prime minister and Cabinet. President Marcos, however, also served (until 1981) as prime minister and ruled by decree. Subsequent amendments and modifications of this constitution replaced the former bicameral legislature with a unicameral body and gave the president even more powers, including the ability to dissolve the legislature and (from 1981) to appoint a prime minister from among members of the legislature.

After the downfall of Marcos in 1986, a new constitution, similar to the 1935 document, was drafted and was ratified in a popular referendum held in February 1987. Its key provision was a return to a bicameral legislature, called the Congress of the Philippines, consisting of a 250-member House of Representatives and a 24-member Senate. However, the 1987 Consitution included several safeguards against the rise of another dictator.

House members are elected from districts, and in 1998, sectoral representatives are elected indirectly through the party list system wherein sectors such as the handicap, women, younth, veterans and elderlies, etc. can form political parties. Member of the house can serve no more than three consecutive three-year terms.

Senators, elected at large, can serve a maximum of two six-year terms. Twelve senate positions are vacated every six years while the other twelve are vacant every six years however, the vacancies are alternate in every three years when the Philippines conduct elections. The first legislative election under the new constitution was held in May 1987.

The president, the head of state, can be elected to only a single six-year term, and the vice president to two consecutive six-year terms. The president appoints the Cabinet, which consists of the heads of the various ministries responsible for running the day-to-day business of the government. Most presidential appointments are subject to the approval of a Commission of Appointments, which consists of equal numbers of senators and representatives.

The country is divided administratively into 79 provinces, which are grouped into 12 regions and 3 autonomous regions; the National Capital Region has a special status. Each province is headed by an elected governor. Local political subdivisions that also have elected officials include cities and municipalities; during the Marcos regime the ancient barangay was reinstated as the smallest unit of government.