Since 1952, Puerto Rico has been a commonwealth of the US, governed under the Puerto Rican Federal Relations Act and under a constitution based on the US model. The Puerto Rican constitution specifically prohibits discrimination "on account of race, color, sex, birth, social origin or condition, or political ideas." The consitution has been amended a number of times, and in 2002, plans to hold a constitutional assembly to amend the constitution were proposed, providing for the elimination of the house of representatives and the senate and the creation of a unicameral legislature.
The commonwealth legislature comprises a senate (Senado) of 27 or more members, 2 from each of 8 senatorial districts, and 11 elected at large; and a house of representatives (Cámara de Representantes) of 51 or more members, 1 from each of 40 districts and 11 at large. Each senate district consists of five house districts. The Law of Minorities holds that if a single party wins two-thirds or more of the seats in either house, but does not win two-thirds of the vote in the gubernatorial election, the opposition parties are eligible for additional seats, in order to give the opposition (collectively) one-third of the seats in either house. The number of seats therefore, can be expanded (up to a limit of 9 in the senate and 17 in the house), if opposition parties receive at least 3% of the gubernatorial vote. In the 2000 election, one seat was added to the senate according to this law, but no seats were added to the house of representatives. Senators must be at least 30 years of age, representatives must be 25. Legislators must have been commonwealth residents for two years and district or municipal residents for one year. All legislators serve four-year terms.
The governor, who may serve an unlimited number of four-year terms, is the only elected executive. Candidates for the governorship must be US citizens for at least five years, must be at least 35 years of age, and must have resided in Puerto Rico for at least five years.
A bill becomes law if approved by both houses and either signed by the governor or left unsigned for 10 days while the legislature is in session. A two-thirds vote of the elected members of each house is sufficient to override a gubernatorial veto. The governor can employ the item veto or reduce amounts in appropriations bills. The governor also has the power to declare martial law in cases of rebellion, invasion, or immediate danger of rebellion or invasion. The constitution may be amended by a two-thirds vote of the legislature and ratification by popular majority vote.
Residents of Puerto Rico may not vote in US presidential elections. A Puerto Rican who settles in one of the 50 states automatically becomes eligible to vote for president; conversely, a state resident who migrates to Puerto Rico forfeits such eligibility. Puerto Rico has no vote in the US Senate or House of Representatives, but a nonvoting resident delegate, elected every four years, may speak on the floor of the House, introduce legislation, and vote in House committees.
Qualified voters must be US citizens, be at least 18 years of age, and have registered 50 days before a general election; absentee registration is not allowed.