Unicameralism (from uni- "one" & Latin camera "chamber") is a type of legislature consisting of one house or assembly that legislates and votes as one. Unicameralism makes up nearly 60% of all national legislatures and an even greater share of subnational legislatures.
Sometimes, as in New Zealand and Denmark, unicameralism comes from the abolition of one of two bicameral chambers, or, as in Sweden, through the merger of the two chambers into a single one, while in others a second chamber has never existed from the beginning.
Rationale for unicameralism and criticism The principal advantage of a unicameral system is more efficient lawmaking, as the legislative process is simpler and there is no possibility of deadlock between two chambers. Proponents of unicameralism have also argued that it reduces costs, even if the number of legislators stays the same, since there are fewer institutions to maintain and support financially. Popular among 20th-century democratic countries, unicameral, proportional legislatures were seen by nascent nations as both more democratic and effective. However, at the tail end of the 20th century, the trend in favour of unicameral legislatures over bicameral legislatures started to reverse, with a trend of countries starting to either restore or create Upper houses with the objectives of achieving greater checks and balances, representation, and/or legislative oversight, causing the number of bicameral parliaments to rise from some 45 countries at the beginning of the 1970s to more than 80 in 2024.
Proponents of bicameral legislatures say that having two legislative chambers offers an additional restraint on the majority, though critics note that there are other ways to restrain majorities, such as through non-partisan courts and a robust constitution.
List of unicameral legislatures
Approximately half of the world's sovereign states are currently unicameral. The People's Republic of China is somewhat in-between, with a legislature and a formal advisory body. China has a Chinese People's Political Consultative Conference which meets alongside the National People's Congress, in many respects an advisory "upper house".
Many subnational entities have unicameral legislatures. These include the state of Nebraska and territories of Guam and the Virgin Islands in the United States, the Chinese special administrative regions of Hong Kong and Macao, the Australian state of Queensland as well as the Northern Territory and the Australian Capital Territory, a majority of the provinces of Argentina, all of the provinces and territories in Canada, all of the Communities, Regions and Community Commissions of Belgium, all of the regions of Italy and France, all of the provinces of Nepal, all of the Spanish autonomous communities, both of the autonomous regions of Portugal, most of the states and union territories of India, and all of the states of Brazil, Mexico, Nigeria, Austria, and Germany. In the United Kingdom, the devolved Scottish Parliament, the Welsh Senedd, the Northern Ireland Assembly, and the London Assembly are also unicameral.
National (UN member states and observers) Federal
Country Unicameral body Seats Notes Assembly of the Union 33 Bundestag 630 The Bundestag is technically the unicameral parliament of Germany, since the Basic Law (German constitution) defines the Bundesrat not as a chamber of the legislature, but as a completely separate legislative institution. Council of Representatives 329 A provision exists for the founding of a "Council of Union", but no move to this effect has been initiated by the existing Council Congress 14 National Assembly 15 Federal National Council 40 National Assembly 285
Unitary
Country Unicameral body Seats Notes Leadership Council30Purely advisory, powers reside in the Supreme Leader Kuvendi140 General Council of Andorra28 National Assembly220 National Assembly105 National Assembly125 Jatiya Sangsad350 National Assembly69 Legislative Council 34Purely advisory, powers reside in the Sultan National Assembly 240 National Assembly127 National Assembly72 National Assembly140 National People's Congress2878 Legislative Assembly57 Sabor151 National Assembly of People's Power470 House of Representatives56 Folketing179 National Assembly65 House of Assembly32 National Parliament65 National Assembly151 Legislative Assembly60 National Assembly150 Riigikogu101 Parliament55 Parliament200 National Assembly58 Parliament150 Parliament276 Parliament300 Congress160 National People's Assembly102 National Assembly65 National Congress128 National Assembly199 Althing63 Islamic Consultative Assembly290 Knesset120 Kurultai145 House of Assembly45 Supreme People's Assembly687 National Assembly 300 National Assembly65 Supreme Council90 National Assembly175 Saeima100 Parliament128 House of Representatives 200 Landtag25 Seimas141 Chamber of Deputies60 National Assembly163Senate suspended due to 2025 coup National Assembly229 Majlis93 National Assembly147 Parliament79 Legislature33 Parliament176 National Assembly66 Parliament101 National Council24 State Great Khural126 Parliament81 Assembly of the Republic250 Parliament19 Parliament123 National Assembly90 National Assembly171 Assembly120 Storting169 Legislative Council132 National Assembly71 National Parliament118 Assembly of the Republic230 Consultative Assembly45 House of Assembly23 Legislative Assembly51 Consultative Assembly150Purely advisory, powers reside in the King Grand and General Council60 National Assembly55 National Assembly165 National Assembly250 National Assembly34 Parliament149 Parliament108 National Council150 National Parliament50 Parliament225 National Assembly51 Riksdag349 People's Assembly210 National Assembly403 Legislative Assembly26 Grand National Assembly600 Assembly125 Parliament16 Parliament529 Verkhovna Rada450 Parliament52 Pontifical Commission8All powers delegated by the sovereign National Assembly500 National Assembly280
Territorial Country Unicameral body Seats Notes Parliament30 House of Assembly13 Parliament21 Legislative Assembly57 House of Representatives41Autonomous region of Papua New Guinea House of Assembly15 Legislative Assembly21 Tribal Council17 Indian reservation of the United States Tribal Council12 Indian reservation of the United States Parliament24 Parliament21 Legislative Assembly11 Løgting33 Assembly57 Parliament17 Inatsisartut31 Autonomous territory of the Kingdom of Denmark Lehislaturan15 Unincorporated territory of the United States States40 Legislative Council90 States Assembly54 Legislative Assembly47 Legislative Assembly33 Legislative Assembly11 Tribal Council24 Indian reservation of the United States Congress54 Assembly20 Island Council10 Territorial Council19 Legislative Council15 Collectivity of Saint Martin23 Territorial Council19 Parliament15 House of Assembly15 General Fono20 House of Assembly21 Legislature15 Territorial Assembly20
State parliaments with limited recognition Country Unicameral body Seats Notes People's Assembly35 Assembly120 Assembly of the Republic50 National Council53 Parliament34 Legislative Yuan113The original constitution is partially superseded by the additional articles only on Taiwan which replaced the tricameral parliament into a unicameral one. A sunset clause in the additional articles will terminate them in the event of a hypothetical resumption of ROC rule in mainland China. Supreme Council33
Subnational Federations
All legislatures and legislative councils of the regions and communities of Belgium All legislative assemblies in all states of Brazil All legislative assemblies of the provinces and territories of Canada All Landtage of the states of Germany All legislative assemblies of the states of Malaysia All legislatures in all states of Mexico All legislatures of the provinces in Nepal All legislatures of the provinces and territories in Pakistan The legislature of the state of Nebraska, and council of the District of Columbia in the United States The tribal councils of the Five Civilized Tribes in the state of Oklahoma Parliament of Queensland and the legislative assemblies of the territories of Australia (but not the other states) Provincial legislatures of the provinces of South Africa Narodna skupština of Republika Srpska 15 of the 23 provinces of Argentina — Chaco, Chubut, Córdoba, Formosa, Jujuy, La Pampa, La Rioja, Misiones, Neuquén, Río Negro, San Juan, Santa Cruz, Santiago del Estero, Tierra del Fuego, Tucumán, and the autonomous city of Buenos Aires. 22 of the 28 states and union territories of India — Arunachal Pradesh, Assam, Chhattisgarh, Goa, Gujarat, Haryana, Himachal Pradesh, Jharkhand, Kerala, Madhya Pradesh, Manipur, Meghalaya, Mizoram, Nagaland, Odisha, Punjab, Rajasthan, Sikkim, Tamil Nadu, Tripura, Uttarakhand, and West Bengal; and 3 of the union territories — Delhi, Jammu and Kashmir, and Puducherry.
Devolved governments Regional councils of France Iraqi Kurdistan Parliament Regional councils of Italy Regional House of Representative councils of Indonesian provinces, regencies, and cities Bangsamoro Parliament in Philippines Parliaments (variously named Parlamento, Cortes, Junta) of the autonomous communities of Spain City and County Councils of the administrative divisions of Taiwan Councils of the oblasts of Ukraine Countries of the United Kingdom: Northern Ireland Assembly Scottish Parliament Welsh Senedd
Others Local People's Congresses of all levels of provinces, regions, and municipalities of the People's Republic of China National Council of the Palestine Liberation Organization
List of historical unicameral legislatures National The First Protectorate Parliament and Second Protectorate Parliament of the Kingdom of England, regulated by the Instrument of Government (dissolved) Parliament of the Kingdom of Scotland until 1707 (dissolved) Congress of the Confederation was unicameral before being replaced in 1789 by the current, bicameral United States Congress. Provisional Congress of the Confederate States was unicameral before being replaced by the bicameral Confederate States Congress in 1862. Ministry of Dáil Éireann of the Irish Republic a revolutionary state between 1919 and 1922 was unicameral during the Irish War of Independence. Replaced by the bicameral Irish Free State government's Seanad (upper house) & Dail (lower house) Congress of Deputies of Second Spanish Republic was unicameral between 1931 and 1936. Dissolved at the end of Spanish Civil War Sejm of Poland under Soviet influence was unicameral between 1947 and 1989. The bicameral parliament was restored following the end of communist rule. The Parliament of Uzbekistan was unicameral before being replaced in 2005 by the current, bicameral Oliy Majlis. National Assembly of Cameroon was unicameral before being replaced in 2013 by the current, bicameral Parliament of Cameroon. Chamber of People's Representative of Equatorial Guinea was unicameral before being replaced in 2013 by the current, bicameral Parliament of Equatorial Guinea. National Assembly of Kenya was the country's unicameral legislature before becoming the lower house of the bicameral Parliament of Kenya in 2013. National Assembly of Ivory Coast was the country's unicameral legislature before becoming the lower house of the bicameral Parliament of Ivory Coast in 2016. Central National Committee and the Provisional People's Representative Council of Indonesia was the unicameral legislature of the Republic of Indonesia during the War of Independence and the liberal democracy era. The National Assembly of Togo The National Assembly of Chad The Assembly of the Representatives of the People of Tunisia The National Assembly of Benin The Congress of the Republic of Peru from 1995 to 2026
Subnational General Assembly of Georgia until 1789 General Assembly of Pennsylvania until 1790 General Assembly of Vermont until 1836
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