A presidential system is a system of government where an |executive branch]] exists and presides (hence the name) separately from the legislature, to which it is not accountable and which cannot, in normal circumstances, dismiss it. 
It owes its origins to the medieval monarchies of France, England and Scotland in which executive authority was vested in the Crown, not in meetings of the estates of the realm (i.e., parliament): the Estates-General of France, the Parliament of England or the Estates of Scotland. The concept of separate spheres of influence of the executive and legislature was copied in the Constitution of the United States, with the creation of the office of President of the United States. Perhaps ironically, in England and Scotland (since 1707 as the Kingdom of Great Britain, and since 1801 as the United Kingdom) the power of a separate executive waned to a ceremonial role and a new executive, answerable to parliament, evolved while the power of the United States's separated executive increased. This has given rise to criticism of the United States presidency as an "imperial presidency" though some analysts dispute the existence of an absolute separation, referring to the concept of "separate institutions sharing power".
The defining characteristic of a republican presidential system is how the executive is elected, but nearly all presidential systems share the following features:
- The president does not propose bills. However, in systems such as that of the United States, the president has the power to veto acts of the legislature and, in turn, a supermajority of legislators may act to override the veto. This practice is derived from the British tradition of royal assent in which an act of parliament cannot come into effect without the assent of the monarch.
- The president has a fixed term of office. Elections are held at scheduled times, and cannot be triggered by a vote of confidence or other such parliamentary procedures. In some countries, including the United States, there is an exception to this rule, which provides for the removal of a president in the event that they are found to have broken a law.
- The executive branch is unipersonal. Members of the cabinet serve at the pleasure of the president and must carry out the policies of the executive and legislative branches. However, presidential systems frequently require legislative approval of presidential nominations to the cabinet as well as various governmental posts such as judges. A president generally has power to direct members of the cabinet, military or any officer or employee of the executive branch, but generally has no power to dismiss or give orders to judges.
- The power to pardon or commute sentences of convicted criminals is often in the hands of the heads of state in governments that separate their legislative and executive branches of government.
- The term presidential system is often used in contrast to cabinet government which is usually a feature of parliamentarism. There also exists a kind of intermediate—the semi-presidential system.
- Countries with congressional and presidential systems include the United States, Indonesia, the Philippines, Mexico, South Korea, Argentina and most countries in South America, as well as much of Africa and the Central Asian Republics. The widespread use of presidentialism in the Americas has caused political scientists to dub the Americas as "the continent of presidentialism".
- Countries that feature a presidential system of government are not the exclusive users of the title of President or the republican form of government. For example, a dictator, who may or may not have been popularly or legitimately elected may be and often is called a president. Likewise, many parliamentary democracies are formally styled republics and have presidents, a position which is largely ceremonial; notable examples include Germany, India, Ireland and Israel (see Parliamentary republic).
Some national presidents are "figurehead" heads of state, like constitutional monarchs, and not active executive heads of government. In a full-fledged presidential system, a president is chosen by the people to be the head of the executive branch.
Presidential governments make no distinction between the positions of head of state and head of government, both of which are held by the president. Most parliamentary governments have a symbolic head of state in the form of a president or monarch. That person is responsible for the formalities of state functions as the figurehead while the constitutional prerogatives of head of government are generally exercised by the prime minister. Such figurehead presidents tend to be elected in a much less direct manner than active presidential-system presidents, for example, by a vote of the legislature. A few nations, such as Ireland, do have a popularly elected ceremonial president.
A few countries (e.g., South Africa) have powerful presidents who are elected by the legislature. These presidents are chosen in the same way as a prime minister, yet are heads of both state and government. These executives are titled "president", but are in practice similar to prime ministers. Other countries with the same system include Botswana, the Marshall Islands, and Nauru. Incidentally, the method of legislative vote for president was a part of Madison's Virginia Plan and was seriously considered by the framers of the American Constitution.
Some political scientists consider the conflation of head-of-state and head-of-government duties to be a problem of presidentialism because criticism of the president as head of state is criticism of the state itself.
Presidents in presidential systems are always active participants in the political process, though the extent of their relative power may be influenced by the political makeup of the legislature and whether their supporters or opponents have the dominant position therein. In some presidential systems such as South Korea or the Republic of China (on Taiwan), there is an office of prime minister or premier but, unlike in semi-presidential or parliamentary systems, the premier is responsible to the president rather than to the legislature.
Supporters generally claim four basic advantages for presidential systems:
- Direct mandate — in a presidential system, the president is often elected directly by the people. To some, this makes the president's power more legitimate than that of a leader appointed indirectly. In the United States, the president is elected neither directly nor through the legislature, but by an electoral college.
- Separation of powers — a presidential system establishes the presidency and the legislature as two parallel structures. Supporters claim that this arrangement allows each structure to supervise the other, preventing abuses.
- Speed and decisiveness — some argue that a president with strong powers can usually enact changes quickly. However, others argue that the separation of powers slows the system down.
- Stability — a president, by virtue of a fixed term, may provide more stability than a prime minister who can be dismissed at any time.
A prime minister is usually chosen by a few individuals of the legislature, while a president is usually chosen by the people. According to supporters of the presidential system, a popularly elected leadership is inherently more democratic than a leadership chosen by a legislative body, even if the legislative body was itself elected, to rule.
Through making more than one electoral choice, voters in a presidential system can more accurately indicate their policy preferences. For example, in the United States of America, some political scientists interpret the late Cold War tendency to elect a Democratic Congress and a Republican president as the choice for a Republican foreign policy and a Democratic domestic policy.
It is also stated that the direct mandate of a president makes him or her more accountable. The reasoning behind this argument is that a prime minister is "shielded" from public opinion by the apparatus of state, being several steps removed. Critics of this view note, however, that presidents cannot typically be removed from power when their policies no longer reflect the wishes of the citizenry. (In the United States, presidents can only be removed by an Impeachment trial for "High Crimes and Misdemeanors," whereas prime ministers can typically be removed if they fail a motion of confidence in their government.)
The fact that a presidential system separates the executive from the legislature is sometimes held up as an advantage, in that each branch may scrutinize the actions of the other. In a parliamentary system, the executive is drawn from the legislature, making criticism of one by the other considerably less likely. A formal condemnation of the executive by the legislature is often regarded to be a vote of no confidence. According to supporters of the presidential system, the lack of checks and balances means that misconduct by a prime minister may never be discovered. Writing about Watergate, Woodrow Wyatt, a former MP in the UK, said "don't think a Watergate couldn't happen here, you just wouldn't hear about it". (ibid)
Critics respond that if a presidential system's legislature is controlled by the president's party, the same situation exists. Proponents note that even in such a situation a legislator from the president's party is in a better position to criticize the president or his policies should he deem it necessary, since a president is immune to the effects of a motion of no confidence. In parliamentary systems, party discipline is much more strictly enforced. If a parliamentary backbencher publicly criticizes the executive or its policies to any significant extent then he/she faces a much higher prospect of losing his/her party's nomination, or even outright expulsion from the party.
Despite the existence of the no confidence vote, in practice, it is extremely difficult to stop a prime minister or cabinet that has made its decision. To vote down important legislation that has been proposed by the cabinet is considered to be a vote of no confidence is thus means the government falls and new elections must be held, a consequence few backbenchers are willing to endure. Hence, a no confidence vote in some parliamentary countries, like Britain, only occurs a few times in a century. In 1931, David Lloyd George told a select committee: "Parliament has really no control over the executive; it is a pure fiction." (Schlesinger 1982)
Speed and decisiveness
Some supporters of presidential systems claim that presidential systems can respond more rapidly to emerging situations than parliamentary ones. A prime minister, when taking action, needs to retain the support of the legislature, but a president is often less constrained. In Why England Slept, future president John F. Kennedy said that Stanley Baldwin and Neville Chamberlain were constrained by the need to maintain the confidence of the Commons.
Other supporters of presidential systems sometimes argue in the exact opposite direction, however, saying that presidential systems can slow decision-making to beneficial ends. Divided government, where the presidency and the legislature are controlled by different parties, is said to restrain the excesses of both parties, and guarantee bipartisan input into legislation. In the United States, Republican Congressman Bill Frenzel wrote in 1995:
- There are some of us who think gridlock is the best thing since indoor plumbing. Gridlock is the natural gift the Framers of the Constitution gave us so that the country would not be subjected to policy swings resulting from the whimsy of the public. And the competition - whether multi-branch, multi-level, or multi-house - is important to those checks and balances and to our ongoing kind of centrist government. Thank heaven we do not have a government that nationalizes one year and privatizes next year, and so on ad infinitum. (Checks and Balances, 8)
Although most parliamentary governments go long periods of time without a no confidence vote, Italy, Israel , and the French Fourth Republic have all experienced difficulties maintaining stability. When parliamentary systems have multiple parties and governments are forced to rely on coalitions, as they do in nations that use a system of proportional representation, extremist parties can theoretically use the threat of leaving a coalition to further their agendas.
Many people consider presidential systems to be more able to survive emergencies. A country under enormous stress may, supporters argue, be better off being led by a president with a fixed term than rotating premierships. France during the Algerian controversy switched to a semi-presidential system as did Sri Lanka during its civil war, while Israel experimented with a directly elected prime minister in 1992. In France and Sri Lanka, the results are widely considered to have been positive. However, in the case of Israel, an unprecedented proliferation of smaller parties occurred, leading to the restoration of the previous system of selecting a prime minister.
The fact that elections are fixed in a presidential system is considered to be a welcome "check" on the powers of the executive, contrasting parliamentary systems, which often allow the prime minister to call elections whenever he sees fit, or orchestrate his own vote of no confidence to trigger an election when he cannot get a legislative item passed. The presidential model is said to discourage this sort of opportunism, and instead force the executive to operate within the confines of a term he cannot alter to suit his own needs. Theoretically, if a president's positions and actions have had a positive impact on their respective country, then it is likely that their party's candidate (possibly they) will be elected for another term in office.