Some representative and constitutional democracies have a presidential system of government, which is based on the separation and sharing of powers among three independent and coordinate branches of government: legislative, executive, and judicial.
The United States is the originator and primary example of the presidential system, a model that is followed in only a few other democracies, such as Argentina, Brazil, Mexico, and the Philippines.
The presidential system, unlike the parliamentary form of democracy, has a strong and independent chief executive with extensive powers related to both domestic, or internal, affairs and foreign policy. The president’s independence from the legislature is based on election by the people to whom he or she is directly accountable and not to the legislature, as in the parliamentary system. Furthermore, the constitution grants strong powers to the chief executive in a presidential system.
In the 70th paper of "The Federalist," Alexander Hamilton argued for a strong presidency, as provided by the U.S. Constitution. He wrote,
Energy in the executive is a leading character in the definition of good government. It is essential to the protection of the community against foreign attacks: it is not less essential to the steady administration of the laws; to the protection of property . . . [and] to the security of liberty against the enterprises and assaults of ambition, of faction, and of anarchy.
In the U.S. presidential system, the President is both the chief executive of the government and the head of state. The President oversees the executive branch of government, which includes the cabinet, or heads of various executive departments, and various administrative bureaus and agencies. The chief executive and the subordinate executive officers have the power and duty to carry out and enforce laws and to administer the day-to-day business of the government. In particular, the President commands the armed forces and is responsible for the defense of the country against internal disorder and foreign attack.
The separate and independent legislative and judicial branches of government, which share power with the executive, prevent the strong executive authority of the presidential system of democracy from becoming excessive or abusive. The bicameral Congress, consisting of the House of Representatives and Senate, is the legislative or lawmaking branch of government in the United States. The judicial branch, which interprets and applies the law in specific cases, includes the Supreme Court, intermediate appellate courts, and district courts at the entry level of jurisdiction.
There are checks and balances among the three separate branches of government, which prevent any one branch from continuously dominating the government, as the legislature does in the parliamentary system of democracy. By contrast with a parliamentary democracy, which permits elections whenever the government loses majority support in the parliament, elected officials in a presidential system serve strictly established terms of office. In the United States, for example, the President serves for four years, members of the Senate for six, and members of the House of Representatives for two. Members of the United States federal judiciary serve lifetime appointments, unless they choose to retire from office.
In the United States, the President, other executive officers, and members of the judiciary can be dismissed through a constitutionally prescribed process of impeachment and conviction, but this has happened only rarely. Members of Congress may force their peers from office for unethical or criminal behavior. This, too, has occurred infrequently. Usually, citizens have no way to force an unpopular President out of power or change the membership of Congress in advance of regularly scheduled elections. Thus, the leading legislative and executive officials in a presidential system of democracy are less immediately accountable to the people than are those in a parliamentary system.
Advocates of the presidential system of democracy claim that it is more stable than the parliamentary alternative. They also say that its complex mechanisms of separated and shared powers, checks and balances, require far more deliberation and compromise of different interests in making laws than occurs in the parliamentary system, thus improving the quality of legislation. Finally, supporters of the presidential form of democracy argue that through separation of powers with checks and balances among the coordinate branches, the presidential system is the best way to achieve limited government and protection of individual rights, especially the rights of minorities.
By John Patrick, Understanding Democracy, A Hip Pocket Guide (Oxford University Press)