One-party state

In a one-party state the ruling party is not one competitor among several but the organising core of the political system. Its leading role is often written into the constitution, it fills the key posts in government, the army, the courts, the media and large enterprises, and independent parties are banned or reduced to licensed satellites. Elections, where held, confirm candidates the party has approved rather than choosing between alternatives.

Samuel Huntington and Clement Moore's 1970 volume treated established one-party systems as a distinct type of modern authoritarianism, born of revolution or anti-colonial struggle and institutionalised through a mass organisation. Later work explains their durability through institutions: Jennifer Gandhi and Adam Przeworski (2007) found that autocrats who use partisan legislatures to incorporate potential opponents survive longer; Jason Brownlee (2007) argued that ruling parties regulate elite conflict and keep defectors inside the regime; and the Geddes–Wright–Frantz data show party-based regimes lasting longer than military or personalist ones. Leninist parties add the nomenklatura system of party control over appointments.

• Constitutional monopoly: the 1977 Soviet constitution called the Communist Party the 'leading and guiding force' of society (Article 6); China's constitution, as amended in 2018, states that the leadership of the Communist Party is the defining feature of socialism with Chinese characteristics (Article 1); Cuba's 2019 constitution calls the Communist Party the 'superior driving force of the society and the State' (Article 5).
• Personnel control: lists of posts that the party fills or approves.
• Parallel hierarchies: party committees shadow state bodies at every level.
• Mass organisations: party-led unions, youth and women's leagues.
• Internal feedback in place of electoral feedback: inspection, petitions and internal reports.

• The Soviet Union (1920s–1990) and the communist states of Eastern Europe until 1989–91.
• China, Vietnam, Laos, Cuba and North Korea today.
• Many post-colonial African states in the 1960s–80s, such as Tanzania under TANU/CCM, where the one-party constitution of 1965 lasted until multiparty politics returned in 1992.

One-party states have ranged from mass terror to milder authoritarianism, but none permits organised opposition. Documented abuses include the Soviet Gulag, the famine that followed China's Great Leap Forward (demographers Ashton and colleagues estimated about 30 million excess deaths in 1958–61), and, according to a 2022 assessment by the UN Office of the High Commissioner for Human Rights, arbitrary and discriminatory detention of Uyghurs and other mainly Muslim groups in Xinjiang that 'may constitute international crimes, in particular crimes against humanity'. China rejects these findings.

Defenders argue that a single party can take a long view, coordinate development and avoid polarised competition; critics answer that without competition there is no peaceful way to remove the leadership, and that information about failures reaches the top late. Whether the rapid growth of China and Vietnam since their market reforms owes anything to one-party rule, or came despite it, is a disputed empirical question.

Party-based autocracies are the most durable type of dictatorship in the comparative data. Most communist one-party states collapsed in 1989–91, while those that combined party control with market reform in Asia, and Cuba, survived.