What Is a Unicameral System? How Legislature Works and Examples

What Is a Unicameral System?

A unicameral system is a government with one legislative house or chamber. Unicameral is the Latin word that describes a single-house legislative system. Countries with unicameral governments include Armenia, Bulgaria, Denmark, Hungary, Slovenia, Ukraine, Serbia, Turkey, and Sweden. Unicameral systems became more popular during the 20th century and some countries, including Greece, New Zealand, and Peru, switched from a bicameral to a unicameral system.

Understanding a Unicameral System

To understand how a unicameral system works, consider the national government of Sweden. Sweden has a parliamentary system with a king as the formal head of the country and the prime minister serving as the seat of executive power.

There are 349 seats in the Parliament and any political party that receives at least 4% of the vote during the national vote is granted seats. The number of seats each party receives is based on the number of votes received and proportional representation by electoral district.

As of 2024, eight parties have seats in Parliament, led by the Social Democrats with 106 seats. The Sweden Democrats are the second largest party with 72 seats and are closely followed by the moderate party with 68 seats. The Left Party and the Centre Party both have 24 seats. The Christian Democrats have 19 seats. Lastly, the Green Party has 18 seats, and the Liberal Party has 16 seats.

Parliament votes on legislative bills, which are proposed by Members of Parliament (MPs) or by the government. All bills except fundamental laws are passed by a simple majority vote of the Parliament. Parliament also approves the prime minister. The Parliament meets annually and elections are held every four years. Neither the prime minister nor MPs have term limits.

Advantages and Disadvantages of a Unicameral System

While the major advantage of a bicameral system is that it can provide checks and balances and prevent potential abuses of power, it can also lead to gridlock which makes the passage of laws difficult.

A major advantage of a unicameral system is that laws can be passed more efficiently. A unicameral system may be able to pass legislation too easily, however, possibly allowing for unpopular laws to be pushed through by the government without a second hurdle to clear.

Special interest groups may influence a unicameral legislature more easily than a bicameral one, and groupthink may be more likely to occur. Because unicameral systems require fewer legislators than bicameral systems, however, they may require less money to operate. These systems may also introduce fewer bills and have shorter legislative sessions.

History of Unicameral Systems

A unicameral system for the U.S. government was proposed by the Articles of Confederation in 1781, but the delegates to the Constitutional Convention in 1787 created a plan for a bicameral system that was modeled on the English system.

America’s founders could not agree on whether the states should each have the same number of representatives or whether the number of representatives should be based on population. The founders decided to do both in an agreement known as the Great Compromise, establishing the bicameral system of the Senate and the House that we still use today.

The U.S. federal government and all the states except Nebraska use a bicameral system while U.S. cities, counties, and school districts commonly use the unicameral system, as do all the Canadian provinces.

Initially, Georgia, Pennsylvania, and Vermont had unicameral legislatures based on the idea that a true democracy should not have two houses representing an upper class and a common class. Instead, a democracy should have a single house representing all people. Each of these states turned to a bicameral system: Georgia in 1789, Pennsylvania in 1790, and Vermont in 1836.

In Australia, three states use a unicameral legislature: Queensland, Northern Territory, and the Australian Capital Territory.

Nebraska's Unicameral System

A Republican named George Norris successfully campaigned to change Nebraska’s legislature from a bicameral to a unicameral system in 1934, and the unicameral model was implemented in 1937. Norris claimed that the bicameral system was outdated, inefficient, and unnecessary.

Norris said a unicameral system could maintain a system of checks and balances by relying on the power of citizens to vote and petition and by relying on the Supreme Court and the governor on matters that required another opinion. Further, a bill may only contain one subject and may not pass until five days after its introduction. Most Nebraska bills also receive a public hearing.

Some countries with unicameral systems have always held such a system while others have changed at some point by merging two houses or abolishing one. New Zealand abolished its upper house in the early 1950s when the National Party took control from the Labour party and voted to do away with the upper house.

Unicameral vs. Bicameral Systems

We've discussed both types of systems above, but let's summarize the difference between a unicameral and bicameral system in its own section. A bicameral system consists of two separate chambers, often referred to as the upper house and the lower house. A unicameral system has only one legislative body.

These structural differences have significant implications for how legislation is passed, the level of checks and balances within the government, and how representative the system is of diverse interests. This dual structure is intended to introduce a layer of checks and balances, ensuring that proposed legislation is carefully examined and debated by two independent bodies. While this system promotes more thorough oversight of laws, it can also slow down the legislative process, as bills must pass through both chambers.

In a bicameral system, the two chambers often serve different purposes and represent different interests. The lower house, such as the U.S. House of Representatives or the UK House of Commons, typically represents the general population based on proportional or regional representation. The upper house, such as the U.S. Senate or the UK House of Lords, may represent regions, states, or other constituencies differently, providing a balance to the lower house’s decisions.

Unicameral systems streamline the legislative process by concentrating all law-making responsibilities within a single chamber. This makes it easier and faster to pass legislation. For smaller nations or those that value efficiency and simplicity, unicameralism can be better (though it still would come with downsides since legislation is easier to pass).

Unicameral vs. Monocameral Systems

The difference between unicameralism and monocameralism lies in the terms used to describe the same legislative structure. Both refer to a system where there is a single legislative chamber responsible for making and passing laws. While "unicameralism" is the more commonly accepted and widely used term, "monocameralism" is a less frequently used synonym.

The fundamental concept behind both terms is the same: a legislature with only one house. Some people may use monocameralism interchangeably with unicameralism to emphasize the singular nature of the legislative body. However, in most cases, the two words mean the same thing and can be used interchangeably.

The Bottom Line

A unicameral system is a form of government with one legislative chamber, which allows for more efficient and cost-effective lawmaking compared to bicameral systems; however, it may also enable the swift passage of unpopular laws without the additional checks provided by a second house.

Some countries, such as Turkey, Sweden, and Ukraine use a unicameral system while in the U.S., Nebraska is the only state that uses one.