The constitution says that the US government consists of 3 branches – the legislative, the executive and the judicial.

Congress is the legislative branch of the government. Its function is to make laws and to finance the operation of government by gathering taxes. The constitution gives Congress the following powers: -to raise money by means of taxes and borrowings; - to coin money and state its value; -to punish counterfeiters; -to make rules for trade with foreign countries and between states; -to set up post offices and federal courts below the Supreme Court; -to organize the armed forces; -to declare war; -to make rules for naturalization of foreign citizens and so on.

Congress is composed of the Senate and the House of Representatives. The term of Congress is two years.

The US Senate has 100 members – 2 from each state. Each Senator is to represent the whole state. Members of the Senate are elected for 6 years but every 2 years one-third of the Senate stands for election. The Senate is presided by the vice-president. He can take part in voting only in the event of a tie-vote.

The Senate has some special powers. It must approve the president’s appointment of ambassadors, Cabinet members and federal judges. The Senate must also approve (by a two-thirds majority vote) a treaty between the US and a foreign country before it becomes a law. The Senate has the sole power to try impeachment cases and to find officials guilty or not guilty.

The House of Representatives consists of 435 members. The number of Representatives, which each state sends to the House, depends on the population, but the constitution says that state should have at least one Representative. The US House of Representatives has special powers of its own. Only a member of the House can introduce a bill to raise money; the House has the sole right to bring charges of misconduct that can lead to an impeachment trial.

Most of the Congress work is done by committees. At present the Senate has 16 standing committees and the House has 22. Each one specializes in a specific area of legislation: foreign affairs, defence, banking, agriculture, commerce and others.

Every bill introduced in either house is referred to a proper committee for study and recommendation. The committee may approve, revise or ignore (Kill) any bill referred to it. The committee process in each house is controlled by the majority party. When a committee has acted favorably on a bill, it is then sent to the floor of the house of origin for open debate. In the Senate the debate is unlimited, while in the House it is limited. When the debate is over, members vote either to approve the bill, defeat it, table it or return it to the committee. A bill passed by one house is sent to the other one for action. If the bill is amended by the second  house, a conference committee composed of members of both houses attempts to reconcile the differences.

Once passed by both houses, the bill is sent to the president. Constitutionally, the president must act on a bill for it to become a law. The president has the option of signing the bill or vetoing it. However, a bill vetoed by the president can be approved by a two-thirds vote of both houses and become a law. The president may also refuse either to sign or veto a bill. In that case, the bill becomes a law without his signature after 10 days (not counting Sundays). The single exception to this rule is when Congress adjourns after sending a bill to the president and before the 10-day period has expired. Such refusal to take any action is known as the "pocket veto”.

The executive branch of government is vested in the president, vice-president and the president’s Cabinet. It is responsible for administering and executing laws.

The president administers national government through instructions to the heads of departments and agencies appointed and removable by him. With the consent of the Senate he appoints the Cabinet members, ambassadors and federal judges. The chief duty of the president is to protect the constitution and enforce the laws passed by Congress. Besides, he has other important powers, too.

The vice-president is elected together with the president for 4 years. He presides over the Senate and votes only in case of a tie-vote. He takes president’s office if the president is unable to finish his term.

The secretaries of the major executive departments are known as the Cabinet. They are not members of Congress and are directly and fully responsible to the president. At present the Cabinet consists of 14 departments: of Agriculture, Commerce, Defense, Education, Energy, Health and human services, Housing and urban development, the Interior, Justice, Labor, State, Transportation, the Treasury, of Veterans affairs. In addition to these departments of the federal government there are agencies and administrations which are also responsible to the president: eg. Central Intelligence Agency, Federal Bureau if Investigation, National Aeronautics and Space Administration, Peace Corps, Federal Election Commission, U.S. Postal Service, etc.

The judiciary of the US is divided into the national (federal) and state judiciaries. Each is independent of the other with the exception that the US Supreme Court may, under special circumstances, review state court decisions.

Article 3 of the Constitution states the basis for the federal court system: "The judicial power of the USA shall be vested in 1 Supreme Court and such inferior courts as the Congress may from time to time establish”. Nowadays the national court system consists of the Supreme Court, 11 courts of appeals, 94 district courts and 3 courts of special jurisdiction. The power of the federal courts extends both to civil and criminal cases arising under federal law. They do not hear cases arising under the laws of individual states. Independence of the judicial power is safeguarded by the Constitution – federal judges are not elected, they are nominated by the president, confirmed by the Senate and hold their office "during good behavior”, in fact, until they die, retire or resign.

The Supreme Court consists of 1 chief justice and 8 associate justices. The Supreme Court sees to it that legislation or executive acts conform to the Constitution, it also hears appeals from lower courts. Its decisions cannot be overruled by any other court. They need not be unanimous, a simple majority prevails, each justice having one vote.

The second highest level of the federal judiciary is made up of the courts of appeals, created in 1891 to ease the burden of the Supreme Court. The USA is divided into 11 appeals regions (circuits), each served by a court of appeals with 3-5 sitting judges. The courts of appeals review decisions of district courts, which are the third level of the federal judiciary and are the main trial courts. Cases start and the judicial procedure is carried on in them. 50 states are divided into 92 districts + 1 in the District of Columbia + 1 in the Commonwealth of Puerto Rico. There are from 1 to 27 judges in each district court. With the exception of the District of Columbia, judges must be residents of the district in which they permanently serve.

In addition to the federal courts of general jurisdiction, it has been necessary to set up courts for special purposes. Perhaps the most important of these is the Court of Claims. Others are the Customs Court and the Court of Customs And Patent Appeals.

The same three-level structure is true for the state courts. Each state has its own Supreme Court, court of appeals and district courts.