A semi-presidential system is a system of government in which a president exists alongside a prime minister and a cabinet, with the latter two being responsible to the legislature of a state. It differs from a parliamentary republic in that it has a popularly elected head of state, who is more than a purely ceremonial figurehead, and from the presidential system in that the cabinet, although named by the president, is responsible to the legislature, which may force the cabinet to resign through a motion of no confidence.
While the German Weimar Republic (1919–1933) exemplified an early semi-presidential system, the term "semi-presidential" was introduced by a 1959 article by journalist Hubert Beuve-Méry and popularized by a 1978 work by political scientist Maurice Duverger, both of which intended to describe the French Fifth Republic (established in 1958).
There are two separate subtypes of semi-presidentialism: premier-presidentialism and president-parliamentarism.
Under the premier-presidential system, the prime minister and cabinet are exclusively accountable to parliament. The president chooses the prime minister and cabinet, but only the parliament may remove them from office with a vote of no confidence. The president does not have the right to dismiss the prime minister or the cabinet. However, in some cases, the president can circumvent this limitation by exercising the discretionary power of dissolving the assembly, which forces the prime minister and cabinet to step down. This subtype is used in Burkina Faso, France, Georgia (since 2013), Lithuania, Madagascar, Mali, Mongolia, Niger, Poland, Portugal, Romania, Senegal, Sri Lanka and Ukraine (since 2014; previously, between 2006 and 2010).
Under the president-parliamentary system, the prime minister and cabinet are dually accountable to the president and the assembly majority. The president chooses the prime minister and the cabinet but must have the support of the parliament majority for his choice. In order to remove a prime minister or the whole cabinet from power, the president can dismiss them or the assembly can remove them by a vote of no confidence. This form of semi-presidentialism is much closer to pure presidentialism. It is used in Armenia, Georgia between 2004 and 2013, Mozambique, Namibia, Russia, Taiwan and Ukraine between 1996 and 2005, and again from 2010 to 2014. It was used in Germany during the Weimarer Republik (Weimar Republic), as the constitutional regime between 1919 and 1933 is called unofficially.
The powers that are divided between president and prime minister can vary greatly between countries.
In France, for example, in case of cohabitation when the president and the prime minister come from opposing parties, the president oversees foreign policy and defence policy (these are generally called les prérogatives présidentielles (the presidential prerogatives)) and the prime minister domestic policy and economic policy. In this case, the division of responsibilities between the prime minister and the president is not explicitly stated in the constitution, but has evolved as a political convention based on the constitutional principle that the prime minister is appointed (with the subsequent approval of a parliament majority) and dismissed by the president. On the other hand, whenever the president is from the same party as the prime minister who leads the conseil de gouvernement (cabinet), he often (if not usually) exercises de facto control over all fields of policy via the prime minister. It is up to the president to decide, how much "autonomy" he leaves to "his" prime minister to act on his own.
In Finland, by contrast, the assignment of responsibility for foreign policy was explicitly stated in the pre-2000 constitution: "foreign policy is led by the president in cooperation with the cabinet".
Semi-presidential systems may sometimes experience periods in which the President and the Prime Minister are from differing political parties. This is called "cohabitation", a term which originated in France when the situation first arose in the 1980s. Cohabitation can create an effective system of checks and balances or a period of bitter and tense stonewalling, depending on the attitudes of the two leaders, the ideologies of their parties, or the demands of their constituencies.
In most cases, cohabitation results from a system in which the two executives are not elected at the same time or for the same term. For example, in 1981, France elected both a Socialist president and legislature, which yielded a Socialist premier. But whereas the president's term of office was for seven years, the National Assembly only served for five. When, in the 1986 legislative election, the French people elected a right-of-centre Assembly, Socialist President Mitterrand was forced into cohabitation with rightist premier Jacques Chirac.
However, in 2000, amendments to the French Constitution reduced the length of the French President's term from seven to five years. This has significantly lowered the chances of cohabitation occurring, as parliamentary and presidential elections may now be conducted within a shorter span of each other.
Italics indicate states with limited recognition.