Political Institutions

In a parliamentary system (the UK), the prime minister comes from the legislature and stays in office only with its support. In a presidential system (Mexico, Nigeria), voters elect the president separately from the legislature. A semi-presidential system (Russia) has both an elected president and a prime minister. Iran and China don't fit neatly: Iran's elected president serves under a Supreme Leader, and China's state posts are controlled by the Communist Party.

Each system has trade-offs. A parliamentary executive usually controls the majority, so it can pass laws quickly, but Parliament can still question ministers, reject bills and bring down the government. Presidential systems separate the branches, which adds checks but can lead to gridlock when the president and legislature disagree.

Executives make and carry out policy, but titles and powers differ. China's top leader is Communist Party General Secretary, state president and head of the military commission; Iran's Supreme Leader outranks the elected president; Russia's president appoints the prime minister; Mexico's and Nigeria's presidents are both head of state and head of government; and the UK prime minister leads the cabinet while the monarch's role is ceremonial.

Term limits stop leaders from ruling indefinitely and bring in new ideas, but they can also push out effective leaders. Mexico's president serves one six-year term, Nigeria's president up to two four-year terms, and Iran's president up to two terms in a row. China removed presidential term limits in 2018, and Russia's 2020 amendments reset the term count for the sitting president.

Other institutions can remove an executive in different ways. The UK House of Commons can bring down a government with a vote of no confidence; Mexico, Nigeria and Russia have impeachment processes; Iran's Assembly of Experts can dismiss the Supreme Leader and the Majles can impeach the president. A UK prime minister can also change between elections when the governing party picks a new leader, as in July 2026. In China, leadership changes are decided inside the Communist Party.

Legislatures make laws, approve budgets and oversee the executive. The UK, Mexico, Nigeria and Russia have two chambers, while Iran's Majles and China's National People's Congress have one. Other bodies can limit a legislature, like China's Politburo Standing Committee or Iran's Guardian Council. Since April 2026 no one sits in the UK House of Lords by inheritance: members are appointed life peers plus 26 Church of England bishops.

Some legislatures truly check the executive through debate, committees, budgets and confidence votes; others mostly approve decisions made elsewhere. The UK Commons questions ministers and scrutinizes laws in committees, China's National People's Congress acts on choices made by Communist Party leaders, and Iran's Guardian Council can block laws the Majles passes.

Courts interpret laws and settle disputes, and countries choose judges differently. The UK Supreme Court (created in 2009) can't strike down Acts of Parliament; China's courts follow the Communist Party (rule by law); Iran's judges apply Islamic law under a judiciary head picked by the Supreme Leader. Mexico now elects its judges by popular vote after a 2024 reform.

An independent judiciary can rule against the government without fear of punishment. Independence depends on how judges are chosen, how long they serve, how they can be removed and how much power courts have to overturn laws. Mexico's 2024 switch to electing judges is a live debate: supporters say it makes judges answer to voters, while critics say it ties them to parties.