Unicameralism

In government, unicameralism (Latin uni, one + camera, chamber) is the practice of having a single legislative or parliamentary chamber. Thus, a unicameral parliament or unicameral legislature is a legislature which consists of one chamber or house.

Concept
Unicameral legislatures exist when there is no widely perceived need for multicameralism. Many multicameral legislatures were created to give separate voices to different sectors of society. Multiple chambers allowed for guaranteed representation of different social classes (as in the Parliament of the United Kingdom or the French States-General), ethnic or regional interests, or subunits of a federation. Where these factors are unimportant, in unitary states with limited regional autonomy, unicameralism often prevails. Sometimes, as in New Zealand and Denmark, this comes about through the abolition of one of the two 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.

The principal advantage of a unicameral system is more efficient lawmaking, as the legislative process is simpler and there is no possibility of deadlock. Proponents of unicameralism have also argued that it reduces costs, even if the number of legislators stay the same, since there are fewer institutions to maintain and support it. However bicameral legislatures offer the opportunity to debate and correct errors in either chamber in parallel, and in some cases to introduce legislation in either chamber. Bicameral legislatures often make provision for experts to participate in lawmaking without being professional politicians.

The main weakness of a unicameral system can be seen as the lack of restraint on the majority, particularly noticeable in parliamentary systems where the leaders of the parliamentary majority also dominate the executive. There is also the risk that important sectors of society may not be adequately represented.

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", so it is in reality neither bicameral nor fully unicameral.

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 Macau, 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 German states, all of the regions of Italy, all of the Spanish autonomous communities, both the autonomous regions of Portugal, most of the states and union territories of India and all of the states of Brazil. In the United Kingdom, the devolved Scottish Parliament, the Senedd, the Northern Ireland Assembly and the London Assembly are also unicameral.

Federal

 * Assembly of the Union of the 🇰🇲 Comoros
 * Council of Representatives of 🇮🇶 Iraq (provision exists for the founding of a "Council of Union", but no move to this effect has been initiated by the existing Council)
 * Congress of 🇫🇲 Micronesia
 * National Assembly of 🇰🇳 Saint Kitts and Nevis
 * Federal National Council of the 🇦🇪 United Arab Emirates
 * National Assembly of 🇻🇪 Venezuela

Unitary

 * National Assembly of 🇦🇱 Albania
 * National Assembly of 🇦🇴 Angola
 * National Assembly of 🇦🇲 Armenia
 * National Assembly of 🇦🇿 Azerbaijan
 * Jatiya Sangsad of 🇧🇩 Bangladesh
 * National Assembly of 🇧🇯 Benin
 * National Assembly of 🇧🇼 Botswana
 * Legislative Council of Brunei
 * National Assembly of 🇧🇬 Bulgaria
 * National Assembly of 🇧🇫 Burkina Faso
 * National Assembly of 🇨🇻 Cape Verde
 * National Assembly of the 🇨🇫 Central African Republic
 * National Assembly of 🇹🇩 Chad
 * National People's Congress of the People's Republic of China - though they also have a Chinese People's Political Consultative Conference which is effectively an advisory "upper house".
 * Parliament of the 🇨🇰 Cook Islands
 * Legislative Assembly of 🇨🇷 Costa Rica
 * Sabor of 🇭🇷 Croatia
 * National Assembly of People's Power of 🇨🇺 Cuba
 * Folketing of 🇩🇰 Denmark
 * House of Assembly of 🇩🇲 Dominica
 * National Assembly of 🇩🇯 Djibouti
 * National Parliament of East Timor
 * National Assembly of 🇪🇨 Ecuador
 * House of Representatives of 🇪🇬 Egypt
 * Legislative Assembly of 🇸🇻 El Salvador
 * National Assembly of 🇪🇷 Eritrea
 * Riigikogu of 🇪🇪 Estonia
 * Parliament of 🇫🇯 Fiji
 * Parliament of 🇫🇮 Finland
 * National Assembly of the 🇬🇲 Gambia
 * Parliament of Georgia
 * Parliament of 🇬🇭 Ghana
 * Parliament of 🇬🇷 Greece
 * Congress of 🇬🇹 Guatemala
 * National Assembly of 🇬🇳 Guinea
 * National People's Assembly of 🇬🇼 Guinea-Bissau
 * National Assembly of 🇬🇾 Guyana
 * National Congress of 🇭🇳 Honduras
 * National Assembly of 🇭🇺 Hungary
 * Althing of 🇮🇸 Iceland
 * Islamic Consultative Assembly of 🇮🇷 Iran
 * Knesset of 🇮🇱 Israel
 * House of Assembly of 🇰🇮 Kiribati
 * Supreme People's Assembly of 🇰🇵 North Korea
 * National Assembly of 🇰🇷 South Korea
 * National Assembly of 🇰🇼 Kuwait
 * Supreme Council of 🇰🇬 Kyrgyzstan
 * National Assembly of Laos
 * Saeima of 🇱🇻 Latvia
 * Parliament of 🇱🇧 Lebanon
 * House of Representatives of 🇱🇾 Libya
 * Landtag of 🇱🇮 Liechtenstein
 * Seimas of 🇱🇹 Lithuania
 * Chamber of Deputies of 🇱🇺 Luxembourg
 * National Assembly of 🇲🇼 Malawi
 * Majlis of the 🇲🇻 Maldives
 * National Assembly of 🇲🇱 Mali
 * Parliament of 🇲🇹 Malta
 * Legislature of the 🇲🇭 Marshall Islands
 * Parliament of 🇲🇷 Mauritania
 * National Assembly of 🇲🇺 Mauritius
 * Parliament of 🇲🇩 Moldova
 * National Council of 🇲🇨 Monaco
 * State Great Khural of 🇲🇳 Mongolia
 * Parliament of 🇲🇪 Montenegro
 * Assembly of the Republic of 🇲🇿 Mozambique
 * Parliament of 🇳🇷 Nauru
 * Parliament of 🇳🇿 New Zealand
 * National Assembly of 🇳🇮 Nicaragua
 * National Assembly of 🇳🇪 Niger
 * Assembly of 🇳🇺 Niue
 * Assembly of North Macedonia
 * Storting of 🇳🇴 Norway
 * Legislative Council of the State of Palestine
 * National Assembly of 🇵🇦 Panama
 * National Parliament of 🇵🇬 Papua New Guinea
 * Congress of the Republic of 🇵🇪 Peru
 * Assembly of the Republic of 🇵🇹 Portugal
 * Consultative Assembly of 🇶🇦 Qatar
 * House of Assembly of 🇻🇨 Saint Vincent and the Grenadines
 * Legislative Assembly of 🇼🇸 Samoa
 * Grand and General Council of 🇸🇲 San Marino
 * National Assembly of São Tomé and Príncipe
 * Consultative Assembly of 🇸🇦 Saudi Arabia (most powers are reserved for the King)
 * National Assembly of 🇸🇳 Senegal
 * National Assembly of 🇷🇸 Serbia
 * National Assembly of 🇸🇨 Seychelles
 * Parliament of 🇸🇱 Sierra Leone
 * Parliament of 🇸🇬 Singapore
 * National Council of 🇸🇰 Slovakia
 * Parliament of 🇱🇰 Sri Lanka
 * National Assembly of 🇸🇷 Suriname
 * Riksdag of 🇸🇪 Sweden
 * Parliament of Syria
 * National Assembly of 🇹🇿 Tanzania
 * National Assembly of 🇹🇬 Togo
 * Legislative Assembly of 🇹🇴 Tonga
 * National Assembly of 🇹🇳 Tunisia
 * Grand National Assembly of 🇹🇷 Turkey
 * Assembly of 🇹🇲 Turkmenistan
 * Parliament of 🇹🇻 Tuvalu
 * Parliament of 🇺🇬 Uganda
 * Verkhovna Rada of 🇺🇦 Ukraine
 * Parliament of 🇻🇺 Vanuatu
 * Pontifical Commission for 🇻🇦 Vatican City State
 * National Assembly of Vietnam
 * National Assembly of 🇿🇲 Zambia

Territorial

 * House of Assembly of the British Virgin Islands
 * Legislative Assembly of the 🇰🇾 Cayman Islands
 * Parliament of 🇬🇱 Greenland
 * The Løgting of the 🇫🇴 Faroe Islands
 * Parliament of 🇬🇮 Gibraltar
 * Legislature of 🇬🇺 Guam
 * Legislative Council of 🇭🇰 Hong Kong
 * Legislative Assembly of Macau
 * Legislative Assembly of the Falkland Islands
 * Legislature of Guam 🇬🇺 Guam
 * Legislature of the U.S. Virgin Islands

State parliaments with limited recognition

 * People's Assembly of Abkhazia
 * National Assembly of the Republic of Artsakh
 * Assembly of Kosovo
 * Assembly of the Republic of Northern Cyprus
 * National Council of the Sahrawi Arab Democratic Republic
 * Parliament of South Ossetia
 * Legislative Yuan of the Republic of China (Taiwan)
 * Supreme Council of Transnistria

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
 * 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 provinces of 🇦🇷 Argentina – Chaco,  Chubut,  Córdoba,  Formosa,  Jujuy,  La Pampa,  La Rioja (Argentina),  Misiones,  Neuquén,  Río Negro (Argentina),  San Juan,  Santa Cruz,  Santiago del Estero,  Tierra del Fuego,  Tucumán and the autonomous city of  Buenos Aires.
 * 22 of the states 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

 * Iraqi Kurdistan Parliament
 * Northern Ireland Assembly
 * 🏴󠁧󠁢󠁳󠁣󠁴󠁿 Scottish Parliament
 * 🏴󠁧󠁢󠁷󠁬󠁳󠁿 Senedd Cymru—the Welsh Parliament
 * Parliaments of the autonomous communities of 🇪🇸 Spain
 * All regional councils of 🇫🇷 France
 * Bangsamoro Parliament

Other

 * 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

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.
 * Congress of Deputies of Second Spanish Republic was unicameral between 1931 and 1936. Dissolved at the end of Spanish Civil War; the present Spanish Parliament (established in 1978) is bicameral.
 * Supreme Assembly of Uzbekistan was unicameral before being replaced in 2005 by the current, bicameral Supreme Assembly.
 * 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.

Subnational

 * General Assembly of Georgia until 1789
 * General Assembly of Pennsylvania until 1790
 * General Assembly of Vermont until 1836

Unicameralism in the United States
Within U.S. states, Nebraska is currently the only state with a unicameral legislature; after a statewide vote, it changed from bicameral to unicameral in 1937. A 2018 study found that efforts to adopt unicameralism in Ohio and Missouri failed due to rural opposition. There was a fear in rural communities that unicameralism would diminish their influence in state government.

Local government legislatures of counties, cities, or other political subdivisions within states are usually unicameral and have limited lawmaking powers compared to their state and federal counterparts.

Some of the 13 colonies which became independent, such as Pennsylvania, New Jersey and New Hampshire had initially introduced strong unicameral legislature and (relatively) less powerful governors with no veto power. Pennsylvania's constitution lasted only 14 years. In 1790, conservatives gained power in the state legislature, called a new constitutional convention, and rewrote the constitution. The new constitution substantially reduced universal male suffrage, gave the governor veto power and patronage appointment authority, and added an upper house with substantial wealth qualifications to the unicameral legislature. Thomas Paine called it a constitution unworthy of America.

In 1999, Governor Jesse Ventura proposed converting the Minnesota Legislature into a single chamber. Although debated, the idea was never adopted.

Seven U.S. states, Arizona, Idaho, Maryland, New Jersey, North Dakota, South Dakota, and Washington, effectively have two-house unicamerals. In these states, districts in the upper house and the lower house are combined into a single constituency, a practice known as nesting.

The U.S. territory of Puerto Rico held a non-binding referendum in 2005. Voters approved changing its Legislative Assembly to a unicameral body by 456,267 votes in favor (83.7%) versus 88,720 against (16.3%). If both the territory's House of Representatives and Senate had approved by a $2/3$ vote the specific amendments to the Puerto Rico Constitution that are required for the change to a unicameral legislature, another referendum would have been held in the territory to approve such amendments. If those constitutional changes had been approved, Puerto Rico could have switched to a unicameral legislature as early as 2015.

On June 9, 2009, the Maine House of Representatives voted to form a unicameral legislature, but the measure did not pass the Senate.

Because of legislative gridlock in 2009, former Congressman Rick Lazio, a prospective candidate for governor, has proposed that New York adopt unicameralism.

The United States as a whole was subject to a unicameral Congress during the years 1781–1788, when the Articles of Confederation were in effect. The Confederate States of America, pursuant to its Provisional Constitution, in effect from February 8, 1861, to February 22, 1862, was governed by a unicameral Congress.

Unicameralism in the Philippines
Though the current Congress of the Philippines is bicameral, the country experienced unicameralism in 1898 and 1899 (during the First Philippine Republic), from 1935 to 1941 ( the Commonwealth era) and from 1943 to 1944 (during the Japanese occupation). Under the 1973 Constitution, the legislative body was called Batasang Pambansa, which functioned also a unicameral legislature within a semi-presidential system form of government until 1986.

The ongoing process of amending or revising the current Constitution and form of government is popularly known as Charter Change. A shift to a unicameral parliament was included in the proposals of the constitutional commission created by former President Gloria Macapagal-Arroyo. Unlike in the United States, senators in the Senate of the Philippines are elected not per district and state but nationally; the Philippines is a unitary state. The Philippine government's decision-making process, relative to the United States, is more rigid, highly centralised, much slower and susceptible to political gridlock. As a result, the trend for unicameralism as well as other political system reforms are more contentious in the Philippines.

While Congress is bicameral, all local legislatures are unicameral: the ARMM Regional Legislative Assembly, the Sangguniang Panlalawigan (Provincial Boards), Sangguniang Panlungsod (City Councils), Sangguniang Bayan (Municipal Councils), Sangguniang Barangay (Barangay Councils) and the Sangguniang Kabataan (Youth Councils).