The Constitution of the United States, signed in 1787, is the nation's governing document. In the first 10 amendments to the Constitution, ratified in 1791 and known as the Bill of Rights, the federal government is denied the power to infringe on rights generally regarded as fundamental to the civil liberties of the people. These amendments prohibit the establishment of a state religion and the abridgment of freedom of speech, press, and the right to assemble. They protect all persons against unreasonable searches and seizures, guarantee trial by jury, and prohibit excessive bail and cruel and unusual punishments. No person may be required to testify against himself, nor may he be deprived of life, liberty, or property without due process of law. The 13th Amendment (1865) banned slavery; the 15th (1870) protected the freed slaves' right to vote; and the 19th (1920) guaranteed the franchise to women. In all, there have been 27 amendments, the last of which, proposed in 1789 but ratified in 1992, denied the variation of the compensation of Senators and Representatives until an election intervened. The Equal Rights Amendment (ERA), approved by Congress in 1972, would have mandated equality between the sexes; only 35 of the required 38 states had ratified the ERA by the time the ratification deadline expired on 30 June 1982.
The United States has a federal form of government, with the distribution of powers between the federal government and the states constitutionally defined. The legislative powers of the federal government are vested in Congress, which consists of the House of Representatives and the Senate. There are 435 members of the House of Representatives. Each state is allotted a number of representatives in proportion to its population as determined by the decennial census. Representatives are elected for two-year terms in every even-numbered year. A representative must be at least 25 years old, must be a resident of the state represented, and must have been a citizen of the United States for at least seven years. The Senate consists of two senators from each state, elected for six-year terms. Senators must be at least 30 years old, must be residents of the states from which they are elected, and must have been citizens of the United States for at least nine years. One-third of the Senate is elected in every even-numbered year.
Congress legislates on matters of taxation, borrowing, regulation of international and interstate commerce, formulation of rules of naturalization, bankruptcy, coinage, weights and measures, post offices and post roads, courts inferior to the Supreme Court, provision for the armed forces, among many other matters. A broad interpretation of the "necessary and proper" clause of the Constitution has widened considerably the scope of congressional legislation based on the enumerated powers.
A bill that is passed by both houses of Congress in the same form is submitted to the president, who may sign it or veto it. If the president chooses to veto the bill, it is returned to the house in which it originated with the reasons for the veto. The bill may become law despite the president's veto if it is passed again by a two-thirds vote in both houses. A bill becomes law without the president's signature if retained for 10 days while Congress is in session. After Congress adjourns, if the president does not sign a bill within 10 days, an automatic veto ensues.
The president must be "a natural born citizen" at least 35 years old, and must have been a resident of the United States for 14 years. Under the 22nd Amendment to the Constitution, adopted in 1951, a president may not be elected more than twice. Each state is allotted a number of electors based on its combined total of US senators and representatives, and, technically, it is these electors who, constituted as the electoral college, cast their vote for president, with all of the state's electoral votes customarily going to the candidate who won the largest share of the popular vote of the state (the District of Columbia also has three electors, making a total of 538 votes). Thus, the candidate who wins the greatest share of the popular vote throughout the United States may, in rare cases, fail to win a majority of the electoral vote. If no candidate gains a majority in the electoral college, the choice passes to the House of Representatives.
The vice president, elected at the same time and on the same ballot as the president, serves as ex officio president of the Senate. The vice president assumes the power and duties of the presidency on the president's removal from office or as a result of the president's death, resignation, or inability to perform his duties. In the case of a vacancy in the vice presidency, the president nominates a successor, who must be approved by a majority in both houses of Congress. The Congress has the power to determine the line of presidential succession in case of the death or disability of both the president and vice president.
Under the Constitution, the president is enjoined to "take care that the laws be faithfully executed." In reality, the president has a considerable amount of leeway in determining to what extent a law is or is not enforced. Congress's only recourse is impeachment, to which it has resorted only three times, in proceedings against presidents Andrew Johnson, Richard Nixon, and Bill Clinton. Both the president and the vice president are removable from office after impeachment by the House and conviction at a Senate trial for "treason, bribery, or other high crimes and misdemeanors." The president has the power to grant reprieves and pardons for offenses against the United States except in cases of impeachment.
The president nominates and "by and with the advice and consent of the Senate" appoints ambassadors, public ministers, consuls, and all federal judges, including the justices of the Supreme Court. As commander in chief, the president is ultimately responsible for the disposition of the land, naval, and air forces, but the power to declare war belongs to Congress. The president conducts foreign relations and makes treaties with the advice and consent of the Senate. No treaty is binding unless it wins the approval of two-thirds of the Senate. The president's independence is also limited by the House of Representatives, where all money bills originate.
The president also appoints as his cabinet, subject to Senate confirmation, the secretaries who head the departments of the executive branch. As of 2003, the executive branch included the following cabinet departments: Agriculture (created in 1862), Commerce (1913), Defense (1947), Education (1980), Energy (1977), Health and Human Services (1980), Housing and Urban Development (1965), Interior (1849), Justice (1870), Labor (1913), State (1789), Transportation (1966), Treasury (1789), Veterans' Affairs (1989), and Homeland Security (2002). The Department of Defense—headquartered in the Pentagon, the world's largest office building—also administers the various branches of the military: Air Force, Army, Navy, defense agencies, and joint-service schools. The Department of Justice administers the Federal Bureau of Investigation, which originated in 1908; the Central Intelligence Agency (1947) is under the aegis of the Executive office. Among the several hundred quasi-independent agencies are the Federal Reserve System (1913), serving as the nation's central bank, and the major regulatory bodies, notably the Environmental Protection Agency (1970), Federal Communications Commission (1934), Federal Power Commission (1920), Federal Trade Commission (1914), and Interstate Commerce Commission (1887).
Regulations for voting are determined by the individual states for federal as well as for local offices, and requirements vary from state to state. In the past, various southern states used literacy tests, poll taxes, "grandfather" clauses, and other methods to disfranchise black voters, but Supreme Court decisions and congressional measures, including the Voting Rights Act of 1965, more than doubled the number of black registrants in Deep South states between 1964 and 1992. In 1960, only 29.1% of the black voting-age population was registered to vote; by the mid-1990s, that percentage had risen to over 65%. By 2003, there were over 12 million registered African American voters. The number of registered Hispanic voters increased from 2.5 million in 1972 to 7.6 million in 2000.