2.1 - Parliamentary, Presidential, and Semi-Presidential Systems
Political systems organize the relationship between the executive (which implements policy) and the legislative (which makes law) branches in different ways. There are three main types: parliamentary, presidential, and semi-presidential.
Parliamentary Systems
Parliamentary systems combine lawmaking and executive functions, with the legislature itself selecting and removing executive leadership.
Key features: the legislature selects the executive, meaning members of parliament vote to choose the head of government. The head of government (Prime Minister, Chancellor) and cabinet are typically members of parliament themselves, so there's a fusion of powers rather than a strict separation. Cabinet ministers answer to parliament collectively, and the legislature can remove the head of government and cabinet through a vote of no confidence. Terms are flexible, meaning government can fall and be replaced without waiting for a scheduled election. And the head of state (a monarch or ceremonial president) is separate from the head of government, who actually holds the real power.
In the UK, Parliament selects the Prime Minister: after an election, whichever party or coalition commands a majority in the House of Commons forms the government, and its leader becomes PM. The PM must be a Member of Parliament, cabinet ministers answer questions in Parliament and face opposition scrutiny, and Parliament can pass a vote of no confidence that forces the government to resign and potentially triggers a new election. The monarch serves a purely ceremonial role while the PM exercises actual executive power.
Boris Johnson became Prime Minister in 2019 after winning a Conservative Party leadership election, not a direct popular vote, and his authority came from commanding a parliamentary majority. When his party withdrew support in 2022, he resigned even though no general election had happened.
The same thing happened in 2026. Keir Starmer became PM after Labour won the July 2024 general election, and in June 2026, days after Andy Burnham won a seat in the Commons in the Makerfield by-election, Starmer announced his resignation under pressure from Labour MPs. Burnham became Labour leader as the only candidate and was appointed PM by King Charles III on July 20, 2026 (see 1.6). As of 2026, Burnham is Prime Minister, and voters never cast a ballot on the change: in a parliamentary system, whoever leads the majority party in the Commons is PM.
Presidential Systems
Presidential systems feature separate elections for the executive and the legislature, with distinct institutions sharing power through checks and balances.
Key features: the president and legislature are elected independently in separate contests, both serve fixed terms, and a single president serves as both head of state (ceremonial functions) and head of government (actual political power). Cabinet officials are appointed by and answerable to the president rather than the legislature, and removing a president requires a formal impeachment process rather than a simple vote. There's a clear separation of powers between branches, and the president claims a direct mandate from voters.
In a presidential system, the cabinet is mostly responsible to the elected executive, not the legislature. The president picks the ministers (sometimes with legislative confirmation, as in Nigeria) and can fire them, but the legislature can't vote them out with a no confidence motion the way a parliament can. The only way a legislature can remove a cabinet member is through impeachment (in Mexico, for example, cabinet secretaries can be impeached by the Chamber of Deputies and tried by the Senate).
Mexico's presidential system has citizens vote separately for president (a single six-year term, called a sexenio, with no reelection) and for the Chamber of Deputies and Senate. The president appoints most cabinet secretaries without legislative confirmation (the main exceptions: the Senate ratifies the Secretary of Foreign Affairs and the Chamber of Deputies ratifies the Secretary of Finance), and Congress can't remove the president except through impeachment for serious crimes. Andrés Manuel López Obrador (AMLO) won the presidency in 2018 for a six-year term, and even after his party lost legislative seats in the 2021 midterms, he stayed president until 2024 since Congress can't force resignation just by voting no confidence. As of 2026, the president is his successor, Claudia Sheinbaum, in office since October 1, 2024, with a term that ends in 2030.
Nigeria's presidential system requires the president to win both a plurality and geographic distribution (25% support in two-thirds of the states) to be directly elected, serving up to two four-year terms. The president appoints ministers subject to Senate confirmation, and impeachment requires a two-thirds vote of all members of each chamber plus an investigation by a seven-person panel that the Chief Justice of Nigeria appoints. Muhammadu Buhari, elected in 2015 and reelected in 2019, served two full terms despite tension with the National Assembly over budgets and appointments, and the legislature couldn't remove him simply for policy disagreements.
Semi-Presidential Systems
Semi-presidential systems blend elements of parliamentary and presidential systems, featuring both a directly elected president and a prime minister who needs legislative approval.
Key features: a dual executive shares power between president and prime minister, with separate elections for president and legislature. The president nominates the prime minister, who must be approved by the legislature, and the cabinet answers to both. The president typically controls foreign policy and defense as head of state, while the prime minister manages day-to-day governance as head of government. The actual balance of power between the two depends heavily on which party controls the legislature.
Russia's semi-presidential system has the president elected by popular vote to a six-year term, while the State Duma is elected separately through a mixed proportional and single-member system. Until 2020 the constitution allowed two consecutive terms, which let Putin step aside in 2008 and come back in 2012; the 2020 amendments changed this to two terms total but reset Putin's count to zero. The president nominates the prime minister, who must be confirmed by the Duma, and while ministers are technically accountable to both president and Duma, the president dominates in practice. Putin nominates prime ministers, including Dmitry Medvedev and Mikhail Mishustin, who function primarily as his subordinates executing his priorities, and since United Russia controls the Duma, confirming his nominees is basically automatic.
Since the 2020 amendments, the Duma also approves the deputy prime ministers and most federal ministers, while the president appoints the ministers in charge of defense, foreign affairs, internal affairs, justice, and other security posts himself after consulting the Federation Council. On paper, this makes the cabinet answer to both the president and the legislature. As of 2026, Putin is in his fifth term (reelected in 2024), Mishustin has been prime minister since 2020, and United Russia won 349 of the 450 Duma seats in the September 2026 election.
Semi-presidential systems can also experience cohabitation, when the president's party doesn't control the legislature, forcing genuine cooperation with an opposition prime minister. France has experienced this when Socialist presidents faced conservative legislative majorities or vice versa. Russia avoids this entirely thanks to United Russia's dominance, keeping power concentrated in the presidency.
Comparing the Three
Parliamentary systems have the executive emerge from and depend on legislative support, making them flexible and responsive to parliamentary majorities. Presidential systems keep the executive independent from the legislature with its own separate mandate, offering stability through fixed terms but risking gridlock. Semi-presidential systems create a hybrid structure with a dual executive, offering flexibility but sometimes creating confusion over who's actually in charge.