Spain is a democratic constitutional monarchy with a ceremonial monarch. Current Prime Minister is Pedro Sánchez, leader of PSOE since 2018. Constitution established in 1978, separating powers into executive, legislative, and judicial branches
UK is a constitutional monarchy with King Charles III as head of state. Parliament consists of House of Commons (650 MPs) and House of Lords (800 peers). Central government holds executive power, with devolved governments in Scotland, Wales, and Northern Ireland
Two-party systems consist of two major political parties dominating the landscape. Win-take-all systems tend to produce two-party systems according to Duverger's law. Systems can be characterized by majority parties or viable third parties
Canada operates as a parliamentary democracy with a federal system. The monarch serves as head of state, while the Prime Minister leads the Cabinet. The Senate has 105 members appointed by the Governor-General. The House of Commons has 338 members elected in single-member districts
Robert Dahl coined the term "polyarchy" to describe government with multiple power holders. Polyarchy differs from democracy by requiring continuous citizen responsiveness. Dahl first implemented polyarchy in US and France, later adopted globally
As of May 2024, there are 393 registered political parties in UK and Northern Ireland. Only registered party names can be used on ballot papers. Parties traditionally were private organizations without state recognition